bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pleiotropic Roles of the Msi1-Like Protein Msl1 in Cryptococcus neoformans
Authors: Yang Dong-Hoon , Maeng Shinae , Strain Anna K. , Floyd Anna , Nielsen Kirsten , Heitman Joseph , Bahn Yong-Sun 
Published: October 2012

ABSTRACT

Msi1-like (MSIL) proteins contain WD40 motifs and have a pleiotropic cellular function as negative regulators of the Ras/cyclic AMP (cAMP) pathway and components of chromatin assembly factor 1 (CAF-1), yet they have not been studied in fungal pathogens. Here we identified and characterized an MSIL protein, Msl1, in
Cryptococcus neoformans
, which causes life-threatening meningoencephalitis in humans. Notably, Msl1 plays pleiotropic roles in
C. neoformans
in both cAMP-dependent and -independent manners largely independent of Ras. Msl1 negatively controls antioxidant melanin production and sexual differentiation, and this was repressed by the inhibition of the cAMP-signaling pathway. In contrast, Msl1 controls thermotolerance, diverse stress responses, and antifungal drug resistance in a Ras/cAMP-independent manner. Cac2, which is the second CAF-1 component, appears to play both redundant and distinct functions compared to the functions of Msl1. Msl1 is required for the full virulence of
C. neoformans
. Transcriptome analysis identified a group of Msl1-regulated genes, which include stress-related genes such as
HSP12
and
HSP78
. In conclusion, this study demonstrates pleiotropic roles of Msl1 in the human fungal pathogen
C. neoformans
, providing insight into a potential novel antifungal therapeutic target.
Rapid Triacylglycerol Turnover in Chlamydomonas reinhardtii Requires a Lipase with Broad Substrate Specificity
Authors: Li Xiaobo , Benning Christoph , Kuo Min-Hao 
Published: October 2012

ABSTRACT

When deprived of nitrogen (N), the photosynthetic microalga
Chlamydomonas reinhardtii
accumulates large quantities of triacylglycerols (TAGs), making it a promising source of biofuel. Prominent transcriptional changes associated with the conditions leading to TAG accumulation have been found, suggesting that the key enzymes for TAG metabolism might be among those that fluctuate in their expression during TAG synthesis and breakdown. Using a
Saccharomyces cerevisiae
lipase null mutant strain for functional complementation, we identified the
CrLIP1
gene from
Chlamydomonas
based on its ability to suppress the lipase deficiency-related phenotypes of the yeast mutant. In
Chlamydomonas
, an inverse correlation was found between the
CrLIP1
transcript level and TAG abundance when
Chlamydomonas
cultures were reversibly deprived of N. The CrLIP1 protein expressed and purified from
Escherichia coli
exhibited lipolytic activity against diacylglycerol (DAG) and polar lipids. The lipase domain of CrLIP1 is most similar to two human DAG lipases, DAGLα and DAGLβ. The involvement of CrLIP1 in
Chlamydomonas
TAG hydrolysis was corroborated by reducing the abundance of the
CrLIP1
transcript with an artificial micro-RNA, which resulted in an apparent delay in TAG lipolysis when N was resupplied. Together, these data suggest that CrLIP1 facilitates TAG turnover in
Chlamydomonas
primarily by degrading the DAG presumably generated from TAG hydrolysis.
Roles of the Structural Symbiosis Polysaccharide (syp) Genes in Host Colonization, Biofilm Formation, and Polysaccharide Biosynthesis in Vibrio fischeri
Authors: Shibata Satoshi , Yip Emily S. , Quirke Kevin P. , Ondrey Jakob M. , Visick Karen L. 
Published: October 2012

ABSTRACTThe symbiosis polysaccharide locus,syp, is required forVibrio fischerito form a symbiotic association with the squidEuprymna scolopes. It is also required for biofilm formation induced by the unlinked regulator RscS. Thesyplocus includes 18 genes that can be classified into four groups based on putative function: 4 genes encode putative regulators, 6 encode glycosyltransferases, 2 encode export proteins, and the remaining 6 encode proteins with other functions, including polysaccharide modification. To understand the roles of each of the 14 structuralsypgenes in colonization and biofilm formation, we generated nonpolar in-frame deletions of each gene. All of the deletion mutants exhibited defects in their ability to colonize juvenile squid, although the impact of the loss of SypB or SypI was modest. Consistent with their requirement for colonization, most of the structural genes were also required for RscS-induced biofilm formation. In particular, the production of wrinkled colonies, pellicles, and the matrix on the colony surface was eliminated or severely decreased in all mutants except for thesypBandsypImutants; in contrast, only a subset of genes appeared to play a role in attachment to glass. Finally, immunoblotting data suggested that the structural Syp proteins are involved in polysaccharide production and/or export. These results provide important insights into the requirements for thesypgenes under different environmental conditions and thus lay the groundwork for a more complete understanding of the matrix produced byV. fischerito enhance cell-cell interactions and promote symbiotic colonization.
Multiple Envelope Stress Response Pathways Are Activated in an Escherichia coli Strain with Mutations in Two Members of the DedA Membrane Protein Family
Authors: Sikdar Rakesh , Simmons Angelica R. , Doerrler William T. 
Published: October 2012

ABSTRACT

We have reported that simultaneous deletion of two
Escherichia coli
genes,
yqjA
and
yghB
, encoding related and conserved inner membrane proteins belonging to the DedA protein family results in a number of intriguing phenotypes, including temperature sensitivity at 42°C, altered membrane lipid composition, and cell division defects. We sought to characterize these and other phenotypes in an effort to establish a function for this protein family in
E. coli
. Here, using reporter assays, we show that the major envelope stress response pathways Cpx, Psp, Bae, and Rcs are activated in strain BC202 (W3110; Δ
yqjA
Δ
yghB
) at the permissive growth temperature of 30°C. We previously demonstrated that 10 mM Mg
2+
, 400 mM NaCl, and overexpression of
tatABC
are capable of restoring normal growth to BC202 at elevated growth temperatures. Deletion of the
cpxR
gene from BC202 results in the loss of the ability of these supplements to restore growth at 42°C. Additionally, we report that the membrane potential of BC202 is significantly reduced and that cell division and growth can be restored either by expression of the multidrug transporter MdfA from a multicopy plasmid or by growth at pH 6.0. Together, these results suggest that the DedA family proteins YqjA and YghB are required for general envelope maintenance and homeostasis of the proton motive force under a variety of growth conditions.
The Zinc-Responsive Regulon of Neisseria meningitidis Comprises 17 Genes under Control of a Zur Element
Authors: Pawlik Marie-Christin , Hubert Kerstin , Joseph Biju , Claus Heike , Schoen Christoph , Vogel Ulrich 
Published: October 2012

ABSTRACT

Zinc is a bivalent cation essential for bacterial growth and metabolism. The human pathogen
Neisseria meningitidis
expresses a homologue of the Zinc uptake regulator Zur, which has been postulated to repress the putative zinc uptake protein ZnuD. In this study, we elucidated the transcriptome of meningococci in response to zinc by microarrays and quantitative real-time PCR (qRT-PCR). We identified 15 genes that were repressed and two genes that were activated upon zinc addition. All transcription units (genes and operons) harbored a putative Zur binding motif in their promoter regions. A meningococcal Zur binding consensus motif (Zur box) was deduced
in silico
, which harbors a conserved central palindrome consisting of hexameric inverted repeats separated by three nucleotides (TGTTAT
DNH
ATAACA).
In vitro
binding of recombinant meningococcal Zur to this Zur box was shown for the first time using electrophoretic mobility shift assays. Zur binding to DNA depended specifically on the presence of zinc and was sensitive to mutations in the palindromic sequence. The Zur regulon among genes of unknown function comprised genes involved in zinc uptake, tRNA modification, and ribosomal assembly. In summary, this is the first study of the transcriptional response to zinc in meningococci.
Conjugal Transfer of a Virulence Plasmid in the Opportunistic Intracellular Actinomycete Rhodococcus equi
Authors: Tripathi V. N. , Harding W. C. , Willingham-Lane J. M. , Hondalus M. K. 
Published: October 2012

ABSTRACT

Rhodococcus equi
is a facultative intracellular, Gram-positive, soilborne actinomycete which can cause severe pyogranulomatous pneumonia with abscessation in young horses (foals) and in immunocompromised people, such as persons with AIDS. All strains of
R. equi
isolated from foals and approximately a third isolated from humans contain a large, ∼81-kb plasmid which is essential for the intramacrophage growth of the organism and for virulence in foals and murine
in vivo
model systems. We found that the entire virulence plasmid could be transferred from plasmid-containing strains of
R. equi
(donor) to plasmid-free
R. equi
strains (recipient) at a high frequency and that plasmid transmission reestablished the capacity for intracellular growth in macrophages. Plasmid transfer required living cells and cell-to-cell contact and was unaffected by the presence of DNase, factors pointing to conjugation as the major means of genetic transfer. Deletion of a putative relaxase-encoding gene,
traA
, located in the proposed conjugative region of the plasmid, abolished plasmid transfer. Reversion of the
traA
mutation restored plasmid transmissibility. Finally, plasmid transmission to other
Rhodococcus
species and some additional related organisms was demonstrated. This is the first study showing a virulence plasmid transfer in
R. equi
, and it establishes a mechanism by which the virulence plasmid can move among bacteria in the soil.
Reexamining Transcriptional Regulation of the
Bacillus subtilis htpX
Gene and the
ykrK
Gene, Encoding a Novel Type of Transcriptional Regulator, and Redefining the YkrK Operator
Authors: Lin Ta-Hui , Huang Shih-Chien , Shaw Gwo-Chyuan 
Published: October 2012

ABSTRACT

HtpX is an integral cytoplasmic membrane metalloprotease well conserved in numerous bacteria. A recent study showed that expression of the
Bacillus subtilis htpX
gene is under dual negative control by Rok and a novel type of transcriptional regulator, YkrK. Here we report that expression of the
B. subtilis htpX
gene is strongly heat inducible. Contrary to the previous prediction,
ykrK
expression has been found to be not subject to autoregulation. We have identified the
htpX
promoter and the authentic
ykrK
promoter, which is also distinct from the previously predicted one. We have redefined a conserved inverted repeat sequence to be the YkrK operator, which is somewhat different from the previously proposed one. We provide evidence that YkrK is not a substrate of HtpX and that heat induction of
htpX
is not YkrK mediated. We have also found that the absence of FtsH or HtpX alone did not impair
B. subtilis
cell viability on LB agar plates at high temperature, whereas the absence of both FtsH and HtpX caused a severe growth defect under heat stress. This finding supports the notion that FtsH and HtpX may have partially overlapping functions in heat resistance. Finally, we show that
htpX
expression is subject to transient negative control by
sigB
under heat stress in a Rok- and YkrK-independent manner. Triple negative control of
htpX
expression at high temperature by
rok
,
sigB
, and
ykrK
may help cells to prevent uncontrolled and detrimental oversynthesis of the HtpX protease.
New Substrates on the Block: Clinically Relevant Resistances for EmrE and Homologues
Authors: Nasie Iris , Steiner-Mordoch Sonia , Schuldiner Shimon 
Published: October 2012

ABSTRACT
Transporters of the small multidrug resistance (SMR) family are small homo- or heterodimers that confer resistance to multiple toxic compounds by exchanging substrate with protons. Despite the wealth of biochemical information on EmrE, the most studied SMR member, a high-resolution three-dimensional structure is missing. To provide proteins that are more amenable to biophysical and structural studies, we identified and partially characterized SMR transporters from bacteria living under extreme conditions of temperature and radiation. Interestingly, these homologues as well as EmrE confer resistance to streptomycin and tobramycin, two aminoglycoside antibiotics widely used in clinics. These are hydrophilic and clinically important substrates of SMRs, and study of their mode of action should contribute to understanding the mechanism of transport and to combating the phenomenon of multidrug resistance. Furthermore, our study of one of the homologues, a putative heterodimer, supports the suggestion that in the SMR family, heterodimers can also function as homodimers.
Polymorphisms in Inc Proteins and Differential Expression ofincGenes among Chlamydia trachomatis Strains Correlate with Invasiveness and Tropism of Lymphogranuloma Venereum Isolates
Authors: Almeida Filipe , Borges Vítor , Ferreira Rita , Borrego Maria José , Gomes João Paulo , Mota Luís Jaime 
Published: October 2012

ABSTRACTChlamydia trachomatisis a human bacterial pathogen that multiplies only within an intracellular membrane-bound vacuole, the inclusion.C. trachomatisincludes ocular and urogenital strains, usually causing infections restricted to epithelial cells of the conjunctiva and genital mucosa, respectively, and lymphogranuloma venereum (LGV) strains, which can infect macrophages and spread into lymph nodes. However,C. trachomatisgenomes display >98% identity at the DNA level. In this work, we studied whetherC. trachomatisInc proteins, which have a bilobed hydrophobic domain that may mediate their insertion in the inclusion membrane, could be a factor determining these different types of infection and tropisms. Analyses of polymorphisms and phylogeny of 48 Inc proteins from 51 strains encompassing the three disease groups showed significant amino acid differences that were mainly due to variations between Inc proteins from LGV and ocular or urogenital isolates. Studies of the evolutionary dynamics ofincgenes suggested that 10 of them are likely under positive selection and indicated that most nonsilent mutations are LGV specific. Additionally, real-time quantitative PCR analyses in prototype and clinical strains covering the three disease groups identified threeincgenes with LGV-specific expression. We determined the transcriptional start sites of these genes and found LGV-specific nucleotides within their promoters. Thus, subtle variations in the amino acids of a subset of Inc proteins and in the expression ofincgenes may contribute to the unique tropism and invasiveness ofC. trachomatisLGV strains.
Biophysical and Bioinformatic Analyses Implicate the Treponema pallidum Tp34 Lipoprotein (Tp0971) in Transition Metal Homeostasis
Authors: Brautigam Chad A. , Deka Ranjit K. , Ouyang Zhiming , Machius Mischa , Knutsen Gregory , Tomchick Diana R. , Norgard Michael V. 
Published: October 2012

ABSTRACT

Metal ion homeostasis is a critical function of many integral and peripheral membrane proteins. The genome of the etiologic agent of syphilis,
Treponema pallidum
, is compact and devoid of many metabolic enzyme genes. Nevertheless, it harbors genes coding for homologs of several enzymes that typically require either iron or zinc. The product of the
tp0971
gene of
T. pallidum
, designated Tp34, is a periplasmic lipoprotein that is thought to be tethered to the inner membrane of this organism. Previous work on a water-soluble (nonacylated) recombinant version of Tp34 established that this protein binds to Zn
2+
, which, like other transition metal ions, stabilizes the dimeric form of the protein. In this study, we employed analytical ultracentrifugation to establish that four transition metal ions (Ni
2+
, Co
2+
, Cu
2+
, and Zn
2+
) readily induce the dimerization of Tp34; Cu
2+
(50% effective concentration [EC
50
] = 1.7 μM) and Zn
2+
(EC
50
= 6.2 μM) were the most efficacious of these ions. Mutations of the crystallographically identified metal-binding residues hindered the ability of Tp34 to dimerize. X-ray crystallography performed on crystals of Tp34 that had been incubated with metal ions indicated that the binding site could accommodate the metals examined. The findings presented herein, coupled with bioinformatic analyses of related proteins, point to Tp34's likely role in metal ion homeostasis in
T. pallidum
.
Genome Sequence of the Bacterium Streptomyces davawensis JCM 4913 and Heterologous Production of the Unique Antibiotic Roseoflavin
Authors: Jankowitsch Frank , Schwarz Julia , Rückert Christian , Gust Bertolt , Szczepanowski Rafael , Blom Jochen , Pelzer Stefan , Kalinowski Jörn , Mack Matthias 
Published: October 2012

ABSTRACT

Streptomyces davawensis
JCM 4913 synthesizes the antibiotic roseoflavin, a structural riboflavin (vitamin B
2
) analog. Here, we report the 9,466,619-bp linear chromosome of
S. davawensis
JCM 4913 and a 89,331-bp linear plasmid. The sequence has an average G+C content of 70.58% and contains six rRNA operons (16S-23S-5S) and 69 tRNA genes. The 8,616 predicted protein-coding sequences include 32 clusters coding for secondary metabolites, several of which are unique to
S. davawensis
. The chromosome contains long terminal inverted repeats of 33,255 bp each and atypical telomeres. Sequence analysis with regard to riboflavin biosynthesis revealed three different patterns of gene organization in
Streptomyces
species. Heterologous expression of a set of genes present on a subgenomic fragment of
S. davawensis
resulted in the production of roseoflavin by the host
Streptomyces coelicolor
M1152. Phylogenetic analysis revealed that
S. davawensis
is a close relative of
Streptomyces cinnabarinus
, and much to our surprise, we found that the latter bacterium is a roseoflavin producer as well.
Bacteremic Pneumonia Caused by Extensively Drug-Resistant Streptococcus pneumoniae
Authors: Kang Cheol-In , Baek Jin Yang , Jeon Kyeongman , Kim So Hyun , Chung Doo Ryeon , Peck Kyong Ran , Lee Nam Yong , Song Jae-Hoon 
Published: October 2012

ABSTRACT

The emergence of antimicrobial resistance threatens the successful treatment of pneumococcal infections. Here we report a case of bacteremic pneumonia caused by an extremely drug-resistant strain of
Streptococcus pneumoniae
, nonsusceptible to at least one agent in all classes but vancomycin and linezolid, posing an important new public health threat in our region.
Role of the SP2 Domain and Its Proteolytic Cleavage in HIV-1 Structural Maturation and Infectivity
Authors: de Marco Alex , Heuser Anke-Mareil , Glass Bärbel , Kräusslich Hans-Georg , Müller Barbara , Briggs John A. G. 
Published: October 2012

ABSTRACT
HIV-1 buds as an immature, noninfectious virion. Proteolysis of its main structural component, Gag, is required for morphological maturation and infectivity and leads to release of four functional domains and the spacer peptides SP1 and SP2. The N-terminal cleavages of Gag and the separation of SP1 from CA are all essential for viral infectivity, while the roles of the two C-terminal cleavages and the role of SP2, separating the NC and p6 domains, are less well defined. We have analyzed HIV-1 variants with defective cleavage at either or both sites flanking SP2, or largely lacking SP2, regarding virus production, infectivity, and structural maturation. Neither the presence nor the proteolytic processing of SP2 was required for particle release. Viral infectivity was almost abolished when both cleavage sites were defective and severely reduced when the fast cleavage site between SP2 and p6 was defective. This correlated with an increased proportion of irregular core structures observed by cryo-electron tomography, although processing of CA was unaffected. Mutation of the slow cleavage site between NC and SP2 or deletion of most of SP2 had only a minor effect on infectivity and did not induce major alterations in mature core morphology. We speculate that not only separation of NC and p6 but also the processing kinetics in this region are essential for successful maturation, while SP2 itself is dispensable.
Complete Genome Sequence of a J Subgroup Avian Leukosis Virus Isolated from Local Commercial Broilers
Authors: Li Hongxin , Xue Chunyi , Ji Jun , Chang Shuang , Shang Huiqin , Zhang Lingjun , Ma Jingyun , Bi Yingzuo , Xie Qingmei 
Published: October 2012

ABSTRACT

Subgroup J avian leukosis virus (ALV-J) isolate GDKP1202 was isolated from a 50-day-old local yellow commercial broiler in the Guangdong province of China in 2012. Here we report the complete genomic sequence of the GDKP1202 isolate, which caused high mortality, serious growth suppression, thymic atrophy, and liver enlargement in commercial broilers. A novel potential binding site (5′-GGCACCTCC-3′) for c-
myb
was identified in the GDKP1202 genome. These findings will provide additional insights into the molecular characteristics in the genomes and pathogenicity of ALV-J.
Complete Genome Sequence of an H9N2 Avian Influenza Virus Isolated from Egret in Lake Dongting Wetland
Authors: Wang Ba , Chen Quanjiao , Chen Ze 
Published: October 2012

ABSTRACT
We isolated a recombinant H9N2 avian influenza virus (AIV) from fresh egret feces in the Ardeidae protection region of the Dongting Lake wetland area in China, and it was designated A/Egret/Hunan/1/2012(H9N2). This is the first report of isolating H9N2 AIV from wild birds in the Dongting Lake wetland. Its eight gene segments are generated by reassortment of gene segments of different AIV subtypes. These results are helpful for understanding the epidemiology and evolution of AIV in wild birds during migration.
Complete Genome Sequence Analysis of a Natural Reassortant Infectious Bursal Disease Virus in China
Authors: Chen Feng , Liu Jiajia , Yan Zhuanqiang , Liu Di , Ji Jun , Qin Jianping , Li Haiyan , Ma Jingyun , Bi Yingzuo , Xie Qingmei 
Published: October 2012

ABSTRACT
A novel isolate of infectious bursal disease virus (IBDV) was designated GX-NN-L. The GX-NN-L IBDV was a very virulent infectious bursal disease virus (vvIBDV) isolated from broiler flocks in Guangxi province, China, in 2011. The GX-NN-L IBDV caused high mortality, immunosuppression, low weight gain, and bursal atrophy in commercial broilers. Here, we report the complete genome sequence of the GX-NN-L IBDV, a reassortment strain with segments A and B derived from very virulent strains and attenuated IBDV, respectively. These findings from this study provide additional insights into the genetic exchange between attenuated and very virulent strains of IBDV and continuous monitoring of the spread of the virus in chicken.
Complete Genome Sequences of Highly Divergent Torque Teno Virus Type I from Swine Herds
Authors: Wang Meng-meng , Zhou Yan-jun , Zhang Qing-zhan , Hou Jun-wei , Yu Hai , Tong Guang-zhi 
Published: October 2012

ABSTRACT
Here, we report three complete genome sequences of porcine torque teno virus type I (TTV1) which were obtained from swine tissues and sera from southern China through routine and nested PCR amplification and characterized together with other genome sequences already deposited in GenBank. The results showed that the TTV1 sequences were highly divergent and could be divided into 1a and 1b subtypes.
Complete Genome Sequence of the Porcine Kobuvirus Variant CH/HNXX-4/2012
Authors: Cao Weijun , Zheng Haixue , Zhang Keshan , Jin Ye , Lv Lv , Yang Fan , Liu Xiangtao 
Published: October 2012

ABSTRACT
Porcine kobuvirus, an emerging virus, may be the underlying etiological cause of a large-scale outbreak of diarrhea in suckling piglets in China that started in 2010. We report the complete genome sequence of the porcine kobuvirus variant CH/HNXX-4/2012 with a 30-amino-acid deletion in its 2B-coding region that was isolated in this outbreak. This will help the phenotypic variation and evolutionary characteristics of porcine kobuvirus to be understood.