bluuebunny/crossref_metadata_2025 huggingface dataset:
Association of Influenza Virus Matrix Protein with Ribonucleoproteins
Authors: Ye Zhiping , Liu Teresa , Offringa Daniel P. , McInnis Jonathan , Levandowski Roland A.
Published: December 2019

To characterize the sites and nature of binding of influenza A virus matrix protein (M1) to ribonucleoprotein (RNP), M1 of A/WSN/33 was altered by deletion or site-directed mutagenesis, expressed in vitro, and allowed to attach to RNP under a variety of conditions. Approximately 70% of the wild-type (Wt) M1 bound to RNP at pH 7.0, but less than 5% of M1 associated with RNP at pH 5.0. Increasing the concentration of NaCl reduced M1 binding, but even at a high salt concentration (0.6 M NaCl), approximately 20% of the input M1 was capable of binding to RNP. Mutations altering potential M1 RNA-binding regions (basic amino acids 101RKLKR105 and the zinc finger motif at amino acids 148 to 162) had varied effect: mutations of amino acids 101 to 105 reduced RNP binding compared to the Wt M1, but mutations of zinc finger motif did not. Treatment of RNP with RNase reduced M1 binding by approximately half, but even M1 mutants lacking RNA-binding regions had residual binding to RNase-treated RNP provided that the N-terminal 76 amino acids of M1 (containing two hydrophobic domains) were intact. Addition of detergent to the reaction mixture further reduced binding related to the N-terminal 76 amino acids and showed the greatest effect for mutations affecting the RNA-binding regions of basic amino acids. The data suggest that M1 interacts with both the RNA and protein components of RNP in assembly and disassembly of influenza A viruses.
Expression of Noncovalent Hepatitis C Virus Envelope E1-E2 Complexes Is Not Required for the Induction of Antibodies with Neutralizing Properties following DNA Immunization
Authors: Fournillier A. , Depla E. , Karayiannis P. , Vidalin O. , Maertens G. , Trépo C. , Inchauspé G.
Published: December 2019

Interactive glycoproteins present on the surface of viral particles represent the main target of neutralizing antibodies. The ability of DNA vaccination to induce antibodies directed at such structures was investigated by using eight different expression plasmids engineered either to favor or to prevent interaction between the hepatitis C virus (HCV) envelope glycoproteins E1 and E2. Independently of the injection route (intramuscular or intraepidermal), plasmids expressing antigens capable of forming heterodimers presumed to be the prebudding form of the HCV envelope protein complex failed to induce any significant, stable antibodies following injection in mice. In sharp contrast, high titers of antibodies directed at both conformational and linear determinants were induced by using plasmids expressing severely truncated antigens that have lost the ability to form native complexes. In addition, only a truncated form of E2 induced antibodies reacting against the hypervariable region 1 of E2 (specifically with the C-terminal part of it) known to contain a neutralization site. When injected intraepidermally into small primates, the truncated E2-encoding plasmid induced antibodies able to neutralize in vitro the binding of a purified E2 protein onto susceptible cells. Because such antibodies have been associated with viral clearance in both humans and chimpanzees, these findings may have important implications for the development of protective immunity against HCV.
Thymocyte-Thymic Epithelial Cell Interaction Leads to High-Level Replication of Human Immunodeficiency Virus Exclusively in Mature CD4+CD8−CD3+Thymocytes: a Critical Role for Tumor Necrosis Factor and Interleukin-7
Authors: Chêne L. , Nugeyre M.-T. , Guillemard E. , Moulian N. , Barré-Sinoussi F. , Israël N.
Published: December 2019

This work aims at identifying the thymocyte subpopulation able to support human immunodeficiency virus (HIV) replication under the biological stimuli of the thymic microenvironment. In this report we demonstrate that interaction with thymic epithelial cells (TEC) induces a high-level replication of the T-tropic primary isolate HIV-1B-LAIpexclusively in the mature CD4+CD8−CD3+thymocytes. Tumor necrosis factor (TNF) and interleukin-7 (IL-7), secreted during this interaction, are critical cytokines for HIV long terminal repeat transactivation through NF-κB-dependent activation. TNF is the major inducer of NF-κB and particularly of the p50-p65 complex, whereas IL-7 acts as a cofactor by sustaining the expression of the p75 TNF receptor. The requirement for TNF is further confirmed by the observation that the inability of the intermediate CD4+CD8−CD3−thymocytes to replicate the virus is associated with a defect in TNF production during their interaction with TEC and correlates with the absence of nuclear NF-κB activity in these freshly isolated thymocytes. Addition of exogenous TNF to the intermediate thymocyte cultures induces NF-κB activity and is sufficient to promote HIV replication in the cocultures with TEC. The other major subpopulation expressing the CD4 receptor, namely, the double-positive (DP) CD4+CD8+CD3±thymocytes, despite the entry of the virus, do not produce a significant level of virus, presumably because they are unresponsive to TNF and IL-7. Together, these data suggest that in vivo, despite an efficient entry of the virus in all the CD4+subpopulations, a high viral load may be generated exclusively within the mature CD4+CD8−CD3+subset of thymocytes. However, under conditions of inflammatory response after infection, TNF might also be present in the intermediate thymocyte compartment, leading to efficient HIV replication in these cells.
A Heterogeneous Nuclear Ribonucleoprotein A/B-Related Protein Binds to Single-Stranded DNA near the 5′ End or within the Genome of Feline Parvovirus and Can Modify Virus Replication
Authors: Wang Dai , Parrish Colin R.
Published: December 2019

Phage display of cDNA clones prepared from feline cells was used to identify host cell proteins that bound to DNA-containing feline panleukopenia virus (FPV) capsids but not to empty capsids. One gene found in several clones encoded a heterogeneous nuclear ribonucleoprotein (hnRNP)-related protein (DBP40) that was very similar in sequence to the A/B-type hnRNP proteins. DBP40 bound specifically to oligonucleotides representing a sequence near the 5′ end of the genome which is exposed on the outside of the full capsid but did not bind most other terminal sequences. Adding purified DBP40 to an in vitro fill-in reaction using viral DNA as a template inhibited the production of the second strand after nucleotide (nt) 289 but prior to nt 469. DBP40 bound to various regions of the viral genome, including a region between nt 295 and 330 of the viral genome which has been associated with transcriptional attenuation of the parvovirus minute virus of mice, which is mediated by a stem-loop structure of the DNA and cellular proteins. Overexpression of the protein in feline cells from a plasmid vector made them largely resistant to FPV infection. Mutagenesis of the protein binding site within the 5′ end viral genome did not affect replication of the virus.
Phase 1 Evaluation of Intranasal Virosomal Influenza Vaccine with and withoutEscherichia coliHeat-Labile Toxin in Adult Volunteers
Authors: Glück Ulrich , Gebbers Jan-Olaf , Glück Reinhard
Published: December 2019

Virosomal vaccines were prepared by extracting hemagglutinin (HA) and neuraminidase from influenza virus and incorporating it in the membranes of liposomes composed of phosphatidylcholine. Two intranasal spray vaccine series were prepared: one series comprised 7.5 μg of HA of each of three strains recommended by the World Health Organization and 1 μg ofEscherichia coliheat-labile toxin (HLT), and the other contained the HA without HLT. In addition, a third vaccine preparation contained 15 μg of HA and 2 μg of HLT. The parenteral virosomal vaccine contained 15 μg of HA without additional adjuvant. The immunogenicity of a single spray vaccination (15 μg of HA and 2 μg of HLT) was compared with that of two vaccinations (7.5 μg of HA with or without 1 μg of HLT) with an interval of 1 week in 60 healthy working adults. Twenty volunteers received one parenteral virosomal vaccine. Two nasal spray vaccinations with HLT-adjuvanted virosomal influenza vaccine induced a humoral immune response which was comparable to that with a single parenteral vaccination. A significantly higher induction of influenza virus-specific immunoglobulin A was noted in the saliva after two nasal applications. The immune response after a single spray vaccination was significantly lower. It could be shown that the use of HLT as a mucosal adjuvant is necessary to obtain a humoral immune response comparable to that with parenteral vaccination. All vaccines were well tolerated.
Primary Human Immunodeficiency Virus Type 2 (HIV-2) Isolates Infect CD4-Negative Cells via CCR5 and CXCR4: Comparison with HIV-1 and Simian Immunodeficiency Virus and Relevance to Cell Tropism In Vivo
Authors: Reeves Jacqueline D. , Hibbitts Sam , Simmons Graham , McKnight Áine , Azevedo-Pereira José M. , Moniz-Pereira José , Clapham Paul R.
Published: December 2019

Cell surface receptors exploited by human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) for infection are major determinants of tropism. HIV-1 usually requires two receptors to infect cells. Gp120 on HIV-1 virions binds CD4 on the cell surface, triggering conformational rearrangements that create or expose a binding site for a seven-transmembrane (7TM) coreceptor. Although HIV-2 and SIV strains also use CD4, several laboratory-adapted HIV-2 strains infect cells without CD4, via an interaction with the coreceptor CXCR4. Moreover, the envelope glycoproteins of SIV of macaques (SIVMAC) can bind to and initiate infection of CD4−cells via CCR5. Here, we show that most primary HIV-2 isolates can infect either CCR5+or CXCR4+cells without CD4. The efficiency of CD4-independent infection by HIV-2 was comparable to that of SIV, but markedly higher than that of HIV-1. CD4-independent HIV-2 strains that could use both CCR5 and CXCR4 to infect CD4+cells were only able to use one of these receptors in the absence of CD4. Our observations therefore indicate (i) that HIV-2 and SIV envelope glycoproteins form a distinct conformation that enables contact with a 7TM receptor without CD4, and (ii) the use of CD4 enables a wider range of 7TM receptors to be exploited for infection and may assist adaptation or switching to new coreceptors in vivo. Primary CD4−fetal astrocyte cultures expressed CXCR4 and supported replication by the T-cell-line-adapted ROD/B strain. Productive infection by primary X4 strains was only triggered upon treatment of virus with soluble CD4. Thus, many primary HIV-2 strains infect CCR5+or CXCR4+cell lines without CD4 in vitro. CD4−cells that express these coreceptors in vivo, however, may still resist HIV-2 entry due to insufficient coreceptor concentration on the cell surface to trigger fusion or their expression in a conformation nonfunctional as a coreceptor. Our study, however, emphasizes that primary HIV-2 strains carry the potential to infect CD4−cells expressing CCR5 or CXCR4 in vivo.
Intracellular Distribution of Rubella Virus Nonstructural Protein P150
Authors: Kujala Pekka , Ahola Tero , Ehsani Neda , Auvinen Petri , Vihinen Helena , Kääriäinen Leevi
Published: December 2019

Antiserum prepared against an amino-terminal fragment of rubella virus (RUB) nonstructural polyprotein was used to study RUB-infected Vero cells. Replicase protein P150 was associated with vesicles and vacuoles of endolysosomal origin and later with large, convoluted, tubular membrane structures. Newly incorporated bromouridine was associated with the same structures and specifically with small membrane invaginations, spherules, indicating that these structures may be the sites of viral RNA synthesis.
Rapid Delivery of Foreign Genes into Plants by Direct Rub-Inoculation with Intact Plasmid DNA of a Tomato Bushy Stunt Virus Gene Vector
Authors: Scholthof Herman B.
Published: December 2019

Tomato bushy stunt virus (TBSV) cDNA, positioned between a modified cauliflower mosaic virus 35S promoter and the hepatitis delta virus antigenomic ribozyme with a downstream nopaline synthase gene polyadenylation signal, established infections upon rub-inoculation of plants with intact plasmids. Application of this methodology produced a TBSV DNA-based gene vector which yielded readily detectable levels of localized foreign gene expression in inoculated leaves. This is the first demonstration of an infectious DNA from a member of the
Tombusviridae
which permits rapid TBSV-mediated foreign-gene expression upon direct rub-inoculation of miniprep DNA onto a variety of plant species.
Improved Production of Gutted Adenovirus in Cells Expressing Adenovirus Preterminal Protein and DNA Polymerase
Authors: Hartigan-O’Connor Dennis , Amalfitano Andrea , Chamberlain Jeffrey S.
Published: December 2019

Production of gutted, or helper-dependent, adenovirus vectors by current methods is inefficient. Typically, a plasmid form of the gutted genome is transfected with helper viral DNA into 293 cells; the resulting lysate is serially passaged to increase the titer of gutted virions. Inefficient production of gutted virus particles after cotransfection is likely due to suboptimal association of replication factors with the abnormal origins found in these plasmid substrates. To test this hypothesis, we explored whether gutted virus production would be facilitated by transfection into cells expressing various viral replication factors. We observed that C7 cells, coexpressing adenoviral DNA polymerase and preterminal protein, converted plasmid DNA into replicating virus approximately 50 times more efficiently than did 293 cells. This property of C7 cells can be used to greatly increase the efficiency of gutted virus production after cotransfection of gutted and helper viral DNA. These cells should also be useful for generation of recombinant adenovirus from any plasmid-based precursor.
Expanded Tropism of Primary Human Immunodeficiency Virus Type 1 R5 Strains to CD4
+
T-Cell Lines Determined by the Capacity To Exploit Low Concentrations of CCR5
Authors: Dejucq Nathalie , Simmons Graham , Clapham Paul R.
Published: December 2019

Human immunodeficiency virus type 1 (HIV-1) non-syncytium-inducing (NSI) strains predominantly use the chemokine receptor CCR5, while syncytium-inducing (SI) strains use CXCR4. In vitro, SI isolates infect and replicate in a range of CD4
+
CXCR4
+
T-cell lines, whereas NSI isolates usually do not. Here we describe three NSI strains that are able to infect two CD4
+
T-cell lines, Molt4 and SupT1. For one strain, a variant of JRCSF selected in vitro, replication on Molt4 was previously shown to be conferred by a single amino-acid change in the V1 loop (M.T. Boyd et al., J. Virol. 67:3649–3652, 1993). On CD4
+
cell lines expressing different coreceptors, these strains use CCR5 predominantly and do not replicate in CCR5-negative peripheral blood mononuclear cells derived from individuals homozygous for Δ32 CCR5. Furthermore, infection of Molt4 and SupT1 by each of these three strains is potently inhibited by ligands for CCR5, including 2D7, a monoclonal antibody specific for CCR5. CCR5 mRNA was present in both Molt4 and SupT1 by reverse transcription-PCR, although CCR5 protein could not be detected either on the cell surface or in intracellular vesicles. The expanded tropism of the three strains shown here is therefore not due to adaptation to a new coreceptor but due to the capacity to exploit extremely low levels of CCR5 on Molt4 and SupT1 cells. This novel tropism observed for a subset of primary HIV-1 isolates may represent an extended tropism to new CD4
+
cell types in vivo.
Identification of Inhibitory Mutants of
Cauliflower mosaic virus
Movement Protein Function after Expression in Insect Cells
Authors: Thomas C. L. , Maule A. J.
Published: December 2019

Cauliflower mosaic virus
(CaMV) encodes a movement protein (MP) which forms tubules in vivo and mediates the translocation of virus particles through plasmodesmata. The relationship between CaMV MP structure and function, in isolation from the complete virus infection, was studied by using MP expression in insect cells. The study allowed the MP domains necessary for tubule formation to be identified and potential MP-MP interactions to be investigated by using double infections with recombinant baculoviruses. Two MP domains which interfered with the ability of the wild-type MP to form tubules were identified. These mutant domains appeared to act as competitive, rather than dominant negative, inhibitors.
Nuclear Transport of the Major Capsid Protein Is Essential for Adeno-Associated Virus Capsid Formation
Authors: Hoque Mainul , Ishizu Ken-ichiro , Matsumoto Akiko , Han Song-Iee , Arisaka Fumio , Takayama Makoto , Suzuki Kenji , Kato Kenzo , Kanda Tadahito , Watanabe Hajime , Handa Hiroshi
Published: December 2019

Adeno-associated virus capsids are composed of three proteins, VP1, VP2, and VP3. Although VP1 is necessary for viral infection, it is not essential for capsid formation. The other capsid proteins, VP2 and VP3, are sufficient for capsid formation, but the functional roles of each protein are still not well understood. By analyzing a series of deletion mutants of VP2, we identified a region necessary for nuclear transfer of VP2 and found that the efficiency of nuclear localization of the capsid proteins and the efficiency of virus-like particle (VLP) formation correlated well. To confirm the importance of the nuclear localization of the capsid proteins, we fused the nuclear localization signal of simian virus 40 large T antigen to VP3 protein. We show that this fusion protein could form VLP, indicating that the VP2-specific region located on the N-terminal side of the protein is not structurally required. This finding suggests that VP3 has sufficient information for VLP formation and that VP2 is necessary only for nuclear transfer of the capsid proteins.
Growth of the Stress-Bearing and Shape-Maintaining Murein Sacculus of
Escherichia coli
Authors: Höltje Joachim-Volker
Published: December 2019

To withstand the high intracellular pressure, the cell wall of most bacteria is stabilized by a unique cross-linked biopolymer called murein or peptidoglycan. It is made of glycan strands [poly-(GlcNAc-MurNAc)], which are linked by short peptides to form a covalently closed net. Completely surrounding the cell, the murein represents a kind of bacterial exoskeleton known as the murein sacculus. Not only does the sacculus endow bacteria with mechanical stability, but in addition it maintains the specific shape of the cell. Enlargement and division of the murein sacculus is a prerequisite for growth of the bacterium. Two groups of enzymes, hydrolases and synthases, have to cooperate to allow the insertion of new subunits into the murein net. The action of these enzymes must be well coordinated to guarantee growth of the stress-bearing sacculus without risking bacteriolysis. Protein-protein interaction studies suggest that this is accomplished by the formation of a multienzyme complex, a murein-synthesizing machinery combining murein hydrolases and synthases. Enlargement of both the multilayered murein of gram-positive and the thin, single-layered murein of gram-negative bacteria seems to follow an inside-to-outside growth strategy. New material is hooked in a relaxed state underneath the stress-bearing sacculus before it becomes inserted upon cleavage of covalent bonds in the layer(s) under tension. A model is presented that postulates that maintenance of bacterial shape is achieved by the enzyme complex copying the preexisting murein sacculus that plays the role of a template.
Vacuole Biogenesis in
Saccharomyces cerevisiae
: Protein Transport Pathways to the Yeast Vacuole
Authors: Bryant Nia J. , Stevens Tom H.
Published: December 2019

Delivery of proteins to the vacuole of the yeast Saccharomyces cerevisiae provides an excellent model system in which to study vacuole and lysosome biogenesis and membrane traffic. This organelle receives proteins from a number of different routes, including proteins sorted away from the secretory pathway at the Golgi apparatus and endocytic traffic arising from the plasma membrane. Genetic analysis has revealed at least 60 genes involved in vacuolar protein sorting, numerous components of a novel cytoplasm-to-vacuole transport pathway, and a large number of proteins required for autophagy. Cell biological and biochemical studies have provided important molecular insights into the various protein delivery pathways to the yeast vacuole. This review describes the various pathways to the vacuole and illustrates how they are related to one another in the vacuolar network of S. cerevisiae.
Molecular Genetics of Mating Recognition in Basidiomycete Fungi
Authors: Casselton Lorna A. , Olesnicky Natalie S.
Published: December 2019

The recognition of compatible mating partners in the basidiomycete fungi requires the coordinated activities of two gene complexes defined as the mating-type genes. One complex encodes members of the homeobox family of transcription factors, which heterodimerize on mating to generate an active transcription regulator. The other complex encodes peptide pheromones and 7-transmembrane receptors that permit intercellular signalling. Remarkably, a single species may have many thousands of cross-compatible mating types because the mating-type genes are multiallelic. Different alleles of both sets of genes are necessary for mating compatibility, and they trigger the initial stages of sexual development—the formation of a specialized filamentous mycelium termed the dikaryon, in which the haploid nuclei remain closely associated in each cell but do not fuse. Three species have been taken as models to describe the molecular structure and organization of the mating-type loci and the genes sequestered within them: the pathogenic smut fungus Ustilago maydis and the mushrooms Coprinus cinereus and Schizophyllum commune. Topics addressed in this review are the roles of the mating-type gene products in regulating sexual development, the molecular basis for multiple mating types, and the molecular interactions that permit different allelic products of the mating type genes to be discriminated. Attention is drawn to the remarkable conservation in the mechanisms that regulate sexual development in basidiomycetes and unicellular ascomycete yeasts, Saccharomyces cerevisiae and Schizosaccharomyces pombe, a theme which is developed in the general conclusion to include the filamentous ascomycetes Neurospora crassa and Podospora anserina.
Acylation ofEscherichia coliHemolysin: A Unique Protein Lipidation Mechanism Underlying Toxin Function
Authors: Stanley Peter , Koronakis Vassilis , Hughes Colin
Published: December 2019

The pore-forming hemolysin (HlyA) of Escherichia coli represents a unique class of bacterial toxins that require a posttranslational modification for activity. The inactive protoxin pro-HlyA is activated intracellularly by amide linkage of fatty acids to two internal lysine residues 126 amino acids apart, directed by the cosynthesized HlyC protein with acyl carrier protein as the fatty acid donor. This action distinguishes HlyC from all bacterial acyltransferases such as the lipid A, lux-specific, and nodulation acyltransferases, and from eukaryotic transferases such as N-myristoyl transferases, prenyltransferases, and thioester palmitoyltransferases. Most lipids directly attached to proteins may be classed as N-terminal amide-linked and internal ester-linked acyl groups and C-terminal ether-linked isoprenoid groups. The acylation of HlyA and related toxins does not equate to these but does appear related to a small number of eukaryotic proteins that include inflammatory cytokines and mitogenic and cholinergic receptors. While the location and structure of lipid moieties on proteins vary, there are common effects on membrane affinity and/or protein-protein interactions. Despite being acylated at two residues, HlyA does not possess a “double-anchor” motif and does not have an electrostatic switch, although its dependence on calcium binding for activity suggests that the calcium-myristoyl switch may have relevance. The acyl chains on HlyA may provide anchorage points onto the surface of the host cell lipid bilayer. These could then enhance protein-protein interactions either between HlyA and components of a host signal transduction pathway to influence cytokine production or between HlyA monomers to bring about oligomerization during pore formation.
Yeast Carbon Catabolite Repression
Authors: Gancedo Juana M.
Published: December 2019

Glucose and related sugars repress the transcription of genes encoding enzymes required for the utilization of alternative carbon sources; some of these genes are also repressed by other sugars such as galactose, and the process is known as catabolite repression. The different sugars produce signals which modify the conformation of certain proteins that, in turn, directly or through a regulatory cascade affect the expression of the genes subject to catabolite repression. These genes are not all controlled by a single set of regulatory proteins, but there are different circuits of repression for different groups of genes. However, the protein kinase Snf1/Cat1 is shared by the various circuits and is therefore a central element in the regulatory process. Snf1 is not operative in the presence of glucose, and preliminary evidence suggests that Snf1 is in a dephosphorylated state under these conditions. However, the enzymes that phosphorylate and dephosphorylate Snf1 have not been identified, and it is not known how the presence of glucose may affect their activity. What has been established is that Snf1 remains active in mutants lacking either the proteins Grr1/Cat80 or Hxk2 or the Glc7 complex, which functions as a protein phosphatase. One of the main roles of Snf1 is to relieve repression by the Mig1 complex, but it is also required for the operation of transcription factors such as Adr1 and possibly other factors that are still unidentified. Although our knowledge of catabolite repression is still very incomplete, it is possible in certain cases to propose a partial model of the way in which the different elements involved in catabolite repression may be integrated.
Biology of Moderately Halophilic Aerobic Bacteria
Authors: Ventosa Antonio , Nieto Joaquín J. , Oren Aharon
Published: December 2019

The moderately halophilic heterotrophic aerobic bacteria form a diverse group of microorganisms. The property of halophilism is widespread within the bacterial domain. Bacterial halophiles are abundant in environments such as salt lakes, saline soils, and salted food products. Most species keep their intracellular ionic concentrations at low levels while synthesizing or accumulating organic solutes to provide osmotic equilibrium of the cytoplasm with the surrounding medium. Complex mechanisms of adjustment of the intracellular environments and the properties of the cytoplasmic membrane enable rapid adaptation to changes in the salt concentration of the environment. Approaches to the study of genetic processes have recently been developed for several moderate halophiles, opening the way toward an understanding of haloadaptation at the molecular level. The new information obtained is also expected to contribute to the development of novel biotechnological uses for these organisms.
Molecular Regulation of β-Lactam Biosynthesis in Filamentous Fungi
Authors: Brakhage Axel A.
Published: December 2019

The most commonly used β-lactam antibiotics for the therapy of infectious diseases are penicillin and cephalosporin. Penicillin is produced as an end product by some fungi, most notably by Aspergillus (Emericella) nidulans and Penicillium chrysogenum. Cephalosporins are synthesized by both bacteria and fungi, e.g., by the fungus Acremonium chrysogenum (Cephalosporium acremonium). The biosynthetic pathways leading to both secondary metabolites start from the same three amino acid precursors and have the first two enzymatic reactions in common. Penicillin biosynthesis is catalyzed by three enzymes encoded by acvA (pcbAB), ipnA (pcbC), and aatA (penDE). The genes are organized into a cluster. In A. chrysogenum, in addition to acvA and ipnA, a second cluster contains the genes encoding enzymes that catalyze the reactions of the later steps of the cephalosporin pathway (cefEF and cefG). Within the last few years, several studies have indicated that the fungal β-lactam biosynthesis genes are controlled by a complex regulatory network, e.g., by the ambient pH, carbon source, and amino acids. A comparison with the regulatory mechanisms (regulatory proteins and DNA elements) involved in the regulation of genes of primary metabolism in lower eukaryotes is thus of great interest. This has already led to the elucidation of new regulatory mechanisms. Furthermore, such investigations have contributed to the elucidation of signals leading to the production of β-lactams and their physiological meaning for the producing fungi, and they can be expected to have a major impact on rational strain improvement programs. The knowledge of biosynthesis genes has already been used to produce new compounds.
Molecular and Biotechnological Aspects of Microbial Proteases
Authors: Rao Mala B. , Tanksale Aparna M. , Ghatge Mohini S. , Deshpande Vasanti V.
Published: December 2019

Proteases represent the class of enzymes which occupy a pivotal position with respect to their physiological roles as well as their commercial applications. They perform both degradative and synthetic functions. Since they are physiologically necessary for living organisms, proteases occur ubiquitously in a wide diversity of sources such as plants, animals, and microorganisms. Microbes are an attractive source of proteases owing to the limited space required for their cultivation and their ready susceptibility to genetic manipulation. Proteases are divided into exo- and endopeptidases based on their action at or away from the termini, respectively. They are also classified as serine proteases, aspartic proteases, cysteine proteases, and metalloproteases depending on the nature of the functional group at the active site. Proteases play a critical role in many physiological and pathophysiological processes. Based on their classification, four different types of catalytic mechanisms are operative. Proteases find extensive applications in the food and dairy industries. Alkaline proteases hold a great potential for application in the detergent and leather industries due to the increasing trend to develop environmentally friendly technologies. There is a renaissance of interest in using proteolytic enzymes as targets for developing therapeutic agents. Protease genes from several bacteria, fungi, and viruses have been cloned and sequenced with the prime aims of (i) overproduction of the enzyme by gene amplification, (ii) delineation of the role of the enzyme in pathogenecity, and (iii) alteration in enzyme properties to suit its commercial application. Protein engineering techniques have been exploited to obtain proteases which show unique specificity and/or enhanced stability at high temperature or pH or in the presence of detergents and to understand the structure-function relationships of the enzyme. Protein sequences of acidic, alkaline, and neutral proteases from diverse origins have been analyzed with the aim of studying their evolutionary relationships. Despite the extensive research on several aspects of proteases, there is a paucity of knowledge about the roles that govern the diverse specificity of these enzymes. Deciphering these secrets would enable us to exploit proteases for their applications in biotechnology.
Revision of the Nomenclature for the
Bacillus thuringiensis
Pesticidal Crystal Proteins
Authors: Crickmore N. , Zeigler D. R. , Feitelson J. , Schnepf E. , Van Rie J. , Lereclus D. , Baum J. , Dean D. H.
Published: December 2019

The crystal proteins of Bacillus thuringiensis have been extensively studied because of their pesticidal properties and their high natural levels of production. The increasingly rapid characterization of new crystal protein genes, triggered by an effort to discover proteins with new pesticidal properties, has resulted in a variety of sequences and activities that no longer fit the original nomenclature system proposed in 1989. Bacillus thuringiensis pesticidal crystal protein (Cry and Cyt) nomenclature was initially based on insecticidal activity for the primary ranking criterion. Many exceptions to this systematic arrangement have become apparent, however, making the nomenclature system inconsistent. Additionally, the original nomenclature, with four activity-based primary ranks for 13 genes, did not anticipate the current 73 holotype sequences that form many more than the original four subgroups. A new nomenclature, based on hierarchical clustering using amino acid sequence identity, is proposed. Roman numerals have been exchanged for Arabic numerals in the primary rank (e.g., Cry1Aa) to better accommodate the large number of expected new sequences. In this proposal, 133 crystal proteins comprising 24 primary ranks are systematically arranged.
Epidemiology, Genetics, and Ecology of Toxigenic
Vibrio cholerae
Authors: Faruque Shah M. , Albert M. John , Mekalanos John J.
Published: December 2019

Cholera caused by toxigenic Vibrio cholerae is a major public health problem confronting developing countries, where outbreaks occur in a regular seasonal pattern and are particularly associated with poverty and poor sanitation. The disease is characterized by a devastating watery diarrhea which leads to rapid dehydration, and death occurs in 50 to 70% of untreated patients. Cholera is a waterborne disease, and the importance of water ecology is suggested by the close association of V. cholerae with surface water and the population interacting with the water. Cholera toxin (CT), which is responsible for the profuse diarrhea, is encoded by a lysogenic bacteriophage designated CTXΦ. Although the mechanism by which CT causes diarrhea is known, it is not clear why V. cholerae should infect and elaborate the lethal toxin in the host. Molecular epidemiological surveillance has revealed clonal diversity among toxigenic V. cholerae strains and a continual emergence of new epidemic clones. In view of lysogenic conversion by CTXΦ as a possible mechanism of origination of new toxigenic clones of V. cholerae, it appears that the continual emergence of new toxigenic strains and their selective enrichment during cholera outbreaks constitute an essential component of the natural ecosystem for the evolution of epidemic V. cholerae strains and genetic elements that mediate the transfer of virulence genes. The ecosystem comprising V. cholerae, CTXΦ, the aquatic environment, and the mammalian host offers an understanding of the complex relationship between pathogenesis and the natural selection of a pathogen.
A Bit of History
Authors: Ingraham John L. , Murray Robert G. E.
Published: December 2019

Reviews of scientific literature began to appear in the 17th century. Journals dedicated to them soon followed, leading eventually to this one, which emerged in the 1930s as Bacteriological Reviews; it adapted to the many changes in our fluid discipline, evolving into the present, much broader Microbiology and Molecular Biology Reviews.
Multiple Pathways of Recombination Induced by Double-Strand Breaks in
Saccharomyces cerevisiae
Authors: Pâques Frédéric , Haber James E.
Published: December 2019

The budding yeast Saccharomyces cerevisiae has been the principal organism used in experiments to examine genetic recombination in eukaryotes. Studies over the past decade have shown that meiotic recombination and probably most mitotic recombination arise from the repair of double-strand breaks (DSBs). There are multiple pathways by which such DSBs can be repaired, including several homologous recombination pathways and still other nonhomologous mechanisms. Our understanding has also been greatly enriched by the characterization of many proteins involved in recombination and by insights that link aspects of DNA repair to chromosome replication. New molecular models of DSB-induced gene conversion are presented. This review encompasses these different aspects of DSB-induced recombination in Saccharomyces and attempts to relate genetic, molecular biological, and biochemical studies of the processes of DNA repair and recombination.
Formation of mRNA 3′ Ends in Eukaryotes: Mechanism, Regulation, and Interrelationships with Other Steps in mRNA Synthesis
Authors: Zhao Jing , Hyman Linda , Moore Claire
Published: December 2019

Formation of mRNA 3′ ends in eukaryotes requires the interaction of transacting factors with cis-acting signal elements on the RNA precursor by two distinct mechanisms, one for the cleavage of most replication-dependent histone transcripts and the other for cleavage and polyadenylation of the majority of eukaryotic mRNAs. Most of the basic factors have now been identified, as well as some of the key protein-protein and RNA-protein interactions. This processing can be regulated by changing the levels or activity of basic factors or by using activators and repressors, many of which are components of the splicing machinery. These regulatory mechanisms act during differentiation, progression through the cell cycle, or viral infections. Recent findings suggest that the association of cleavage/polyadenylation factors with the transcriptional complex via the carboxyl-terminal domain of the RNA polymerase II (Pol II) large subunit is the means by which the cell restricts polyadenylation to Pol II transcripts. The processing of 3′ ends is also important for transcription termination downstream of cleavage sites and for assembly of an export-competent mRNA. The progress of the last few years points to a remarkable coordination and cooperativity in the steps leading to the appearance of translatable mRNA in the cytoplasm.
Alkaliphiles: Some Applications of Their Products for Biotechnology
Authors: Horikoshi Koki
Published: December 2019

The term “alkaliphile” is used for microorganisms that grow optimally or very well at pH values above 9 but cannot grow or grow only slowly at the near-neutral pH value of 6.5. Alkaliphiles include prokaryotes, eukaryotes, and archaea. Many different taxa are represented among the alkaliphiles, and some of these have been proposed as new taxa. Alkaliphiles can be isolated from normal environments such as garden soil, although viable counts of alkaliphiles are higher in samples from alkaline environments. The cell surface may play a key role in keeping the intracellular pH value in the range between 7 and 8.5, allowing alkaliphiles to thrive in alkaline environments, although adaptation mechanisms have not yet been clarified. Alkaliphiles have made a great impact in industrial applications. Biological detergents contain alkaline enzymes, such as alkaline cellulases and/or alkaline proteases, that have been produced from alkaliphiles. The current proportion of total world enzyme production destined for the laundry detergent market exceeds 60%. Another important application is the industrial production of cyclodextrin by alkaline cyclomaltodextrin glucanotransferase. This enzyme has reduced the production cost and paved the way for cyclodextrin use in large quantities in foodstuffs, chemicals, and pharmaceuticals. It has also been reported that alkali-treated wood pulp could be biologically bleached by xylanases produced by alkaliphiles. Other applications of various aspects of alkaliphiles are also discussed.
The central role of CT coronary angiography in postcardiac arrest care in the young adult
Authors: Khan-Kheil Ayisha Mehtab , Moss Alexandra Sophie , Stephens Leanne , Khan Jamal Nasir
Published: December 2019

A 32-year-old man with no medical history went into ventricular fibrillation while running at the gym. He was transferred to our tertiary centre post successful resuscitation where admission electrocardiography and echocardiography were unremarkable. The initial cause of cardiac arrest was suspected arrhythmogenic and he was admitted for further investigations including exercise testing, ajmaline challenge, CT coronary angiography (CTCA) and cardiovascular MRI, with the likely outcome of cardioverter-defibrillator implantation. CTCA, however, revealed significant stenosis in the proximal left anterior descending artery as the likely cause for his arrest. Invasive coronary angiography confirmed this and facilitated successful stent implantation, avoiding the need for implantable cardioverter-defibrillator implantation. This case highlights the importance of CTCA, a non-invasive and readily-available test in the investigation of young patients postcardiac arrest, who require active exclusion of coronary artery disease and anomalous coronary anatomy, though they represent a low-risk population group.
Future of information technology and telecommunication in type 1 diabetes clinical care: results of an online survey
Authors: Haluza Daniela , Lang Samantha , Rogers Helen , Harris Sophie , Jungwirth David , Choudhary Pratik , Schuetz-Fuhrmann Ingrid , Stadler Marietta
Published: December 2019

Objective

To assess the attitude of people living with type 1 diabetes toward the use of information and communication technology (ICT) to facilitate access to diabetes healthcare professionals (HCPs).

Research design and methods

We conducted a cross-sectional online survey in two European tertiary diabetes care centers in London, UK, and Vienna, Austria, and from online diabetes platforms. Participants were asked about general options of online diabetes care and were presented with three scenarios (teleconference, online chat and telemonitoring of continuous glucose monitoring traces).

Results

In total, 294 people (59% female; 78 British, 164 Austrians, 47 Germans, 5 from other countries; 45±15 years) who had been living with type 1 diabetes for 26±14.5 years participated. The vast majority of participants were insulin pump (and/or glucose sensor) users (84%) and reported good glycemic control (31% with hemoglobin A1c (HbA1c) <7% and 51% with HbA1c 7%–8%). ICT was generally acceptable for counseling, with email/online messaging services and online health platform the most preferred options (74% and 53%). Study participants expressed a neutral to positive attitude toward the combined theme scores (relationship with HCP; confidence using technology; trust in data protection; intrusion of patient privacy; general acceptance of ICT in healthcare). UK participants showed more positive attitudes toward ICT across all theme scores than participants from Austria and Germany, but there were no gender-related differences.

Conclusions

This online survey identified a highly ICT-astute group of people with type 1 diabetes, already using technology for insulin delivery, for whom online supported clinical diabetes care would be a viable and welcomed option.
Experience of and access to maternity care in the UK by immigrant women: a narrative synthesis systematic review
Authors: Higginbottom Gina Marie Awoko , Evans Catrin , Morgan Myfanwy , Bharj Kuldip Kaur , Eldridge Jeanette , Hussain Basharat
Published: December 2019

One in four births in the UK is to foreign-born women. In 2016, the figure was 28.2%, the highest figure on record, with maternal and perinatal mortality also disproportionately higher for some immigrant women. Our objective was to examine issues of access and experience of maternity care by immigrant women based on a systematic review and narrative synthesis of empirical research.

Review methods

A research librarian designed the search strategies (retrieving literature published from 1990 to end June 2017). We retrieved 45 954 citations and used a screening tool to identify relevance. We searched for grey literature reported in databases/websites. We contacted stakeholders with expertise to identify additional research.

Results

We identified 40 studies for inclusion: 22 qualitative, 8 quantitative and 10 mixed methods. Immigrant women, particularly asylum-seekers, often booked and accessed antenatal care later than the recommended first 10 weeks. Primary factors included limited English language proficiency, lack of awareness of availability of the services, lack of understanding of the purpose of antenatal appointments, immigration status and income barriers. Maternity care experiences were both positive and negative. Women with positive perceptions described healthcare professionals as caring, confidential and openly communicative in meeting their medical, emotional, psychological and social needs. Those with negative views perceived health professionals as rude, discriminatory and insensitive to their cultural and social needs. These women therefore avoided continuously utilising maternity care.

We found few interventions focused on improving maternity care, and the effectiveness of existing interventions have not been scientifically evaluated.

Conclusions

The experiences of immigrant women in accessing and using maternity care services were both positive and negative. Further education and training of health professionals in meeting the challenges of a super-diverse population may enhance quality of care, and the perceptions and experiences of maternity care by immigrant women.
Building research capacity through programme development and research implementation in resource-limited settings - the Ipabalele study protocol: observational cohort studies determining the effect of HIV on the natural history of cervical cancer in Botswana
Authors: Grover Surbhi , Zetola Nicola , Ramogola-Masire Doreen , Bvochora-Nsingo Memory , Schnader Allison F , Mick Rosemarie , Gabaitiri Lesego , Matlhagela Keikantse , Shen Hao , Chiyapo Sebathu , Balang Dawn , Phaladze Nthabiseng , Nkomazana Oathokwa , Friedman Harvey , Jemmott John , Chilisa Bagele , Robertson Erle S
Published: December 2019

Introduction

The global burden of cancer continues to increase in low- and middle-income countries, particularly in sub-Saharan Africa (SSA). Botswana, a middle-income country in SSA, has the second highest prevalence of HIV worldwide and has seen an increase in human papillomavirus (HPV)-associated cervical cancer over the last decade in the setting of improved survival of HIV-infected women. There is an urgent need to understand more clearly the causes and consequences of HPV-associated cervical cancer in the setting of HIV infection. We initiated the Ipabalele (‘take care of yourself’ in Setswana) programme to address this need for new knowledge and to initiate long-term research programme capacity building in the region. In this manuscript, we describe the components of the programme, including three main research projects as well as a number of essential cores to support the activities of the programme.

Methods and procedures

Our multidisciplinary approach aims to further current understanding of the problem by implementing three complementary studies aimed at identifying its molecular, behavioural and clinical determinants. Three participant cohorts were designed to represent the early, intermediate and late stages of the natural history of cervical cancer.

The functional structure of the programme is coordinated through programmatic cores. These allow for integration of each of the studies within the cohorts while providing support for pilot studies led by local junior investigators. Each project of the Ipabalele programme includes a built-in capacity building component, promoting the establishment of long-lasting infrastructure for future research activities.

Ethics and dissemination

Institutional review board approvals were granted by the University of Pennsylvania, University of Botswana and Ministry of Health and wellness of Botswana. Results will be disseminated via the participating institutions and with the help of the Community Advisory Committee, the project’s Botswana advisory group.