bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of Potent Bactericidal Compounds Produced by Escapin, an
l
-Amino Acid Oxidase in the Ink of the Sea Hare
Aplysia californica
Authors: Ko Ko-Chun , Wang Binghe , Tai Phang C. , Derby Charles D. 
Published: October 2008

ABSTRACT

The ink of sea hares (
Aplysia californica
) contains escapin, an
l
-amino acid oxidase that metabolizes
l
-lysine, thereby producing a mixture that kills microbes and deters attacking predators. This secretion contains H
2
O
2
, ammonia, and an equilibrium mixture of “escapin intermediate product” (EIP-K) that includes α-keto-ε-aminocaproic acid and several other molecules. Components of the equilibrium mixture react nonenzymatically with H
2
O
2
to form “escapin end product” (EEP-K), which contains δ-aminovaleric acid and δ-valerolactam. The proportions of the molecules in this equilibrium mixture change with pH, and this is biologically important because the secretion is pH 5 when released but becomes pH 8 when fully diluted in seawater. The goal of the current study was to identify which molecules in this equilibrium mixture are bactericidal. We show that a mixture of H
2
O
2
and EIP-K, but not EEP-K, at low mM concentrations is synergistically responsible for most of the bactericidal activity of the secretion against
Escherichia coli
,
Vibrio harveyi
,
Staphylococcus aureus
, and
Pseudomonas aeruginosa
. Low pH enhances the bactericidal effect, and this does not result from stress associated with low pH itself. Sequential exposure to low mM concentrations of EIP-K and H
2
O
2
, in either order, does not kill
E. coli
. Reaction products formed when
l
-arginine is substituted for
l
-lysine have almost no bactericidal activity. Our results favor the idea that the bactericidal activity is due to unstable intermediates of the reaction of α-keto-ε-aminocaproic acid with H
2
O
2
.
Cross-Kingdom Amplification Using
Bacteria
-Specific Primers: Complications for Studies of Coral Microbial Ecology
Authors: Galkiewicz Julia P. , Kellogg Christina A. 
Published: October 2008

ABSTRACT

PCR amplification of pure bacterial DNA is vital to the study of bacterial interactions with corals. Commonly used
Bacteria
-specific primers 8F and 27F paired with the universal primer 1492R amplify both eukaryotic and prokaryotic rRNA genes. An alternative primer set, 63F/1542R, is suggested to resolve this problem.
Novel Cold-Adapted Alkaline Lipase from an Intertidal Flat Metagenome and Proposal for a New Family of Bacterial Lipases
Authors: Kim Eun-Young , Oh Ki-Hoon , Lee Mi-Hwa , Kang Chul-Hyung , Oh Tae-Kwang , Yoon Jung-Hoon 
Published: October 2008

ABSTRACT
A new lipase, LipEH166, isolated from an intertidal flat metagenome, showed no amino acid similarity to any known lipolytic enzyme except in the consensus region. This suggested that LipEH166 and its homologues belong to a new family of lipolytic enzymes. Partial characterization indicated that LipEH166 is a novel cold-adapted alkaline lipase.
Adenoviruses in Immunocompromised Hosts
Authors: Echavarría Marcela 
Published: October 2008

SUMMARYThe number of patients with acquired immunodeficiency has grown steadily as a result of both a larger number of patients receiving solid organ and hematopoietic stem cell transplants and their longer survival times. The use of newer, more potent immunosuppressive regimens has increased the frequency of severe adenovirus infections. Human adenoviruses are a large group of viruses, represented by at least 52 serotypes with various genotypes divided into genomic clusters, and these may cause a broad variety of clinical manifestations. The development of molecular methods has increased the sensitivity and rapidity of adenovirus infection diagnosis. The implementation of PCR assays has significantly contributed to the identification of patients with disseminated adenovirus disease. More recently, the development of real-time PCR assays has permitted virus quantification and patient follow-up. There is no treatment for adenovirus with demonstrated efficacy, although cidofovir is widely used. Sensitive diagnostic tests for adenovirus can contribute to the early diagnosis and successful treatment of life-threatening adenovirus infections, especially in complex immunocompromised patients. The development of improved adenovirus therapy still remains a challenge. Adenovirus genetic diversity should be considered for diagnosis, typing, and therapeutic interventions.
A
Phytophthora sojae
G-Protein α Subunit Is Involved in Chemotaxis to Soybean Isoflavones
Authors: Hua Chenlei , Wang Yonglin , Zheng Xiaobo , Dou Daolong , Zhang Zhengguang , Govers Francine , Wang Yuanchao 
Published: October 2008

ABSTRACT

For the soybean pathogen
Phytophthora sojae
, chemotaxis of zoospores to isoflavones is believed to be critical for recognition of the host and for initiating infection. However, the molecular mechanisms underlying this chemotaxis are largely unknown. To investigate the role of G-protein and calcium signaling in chemotaxis, we analyzed the expression of several genes known to be involved in these pathways and selected one that was specifically expressed in sporangia and zoospores but not in mycelium. This gene, named
PsGPA1
, is a single-copy gene in
P. sojae
and encodes a G-protein α subunit that shares 96% identity in amino acid sequence with that of
Phytophthora infestans
. To elucidate the function, expression of
PsGPA1
was silenced by introducing antisense constructs into
P. sojae. PsGPA1
silencing did not disturb hyphal growth or sporulation but severely affected zoospore behavior, including chemotaxis to the soybean isoflavone daidzein. Zoospore encystment and cyst germination were also altered, resulting in the inability of the
PsGPA1
-silenced mutants to infect soybean. In addition, the expressions of a calmodulin gene,
PsCAM1
, and two calcium- and calmodulin-dependent protein kinase genes,
PsCMK3
and
PsCMK4
, were increased in the mutant zoospores, suggesting that
PsGPA1
negatively regulates the calcium signaling pathways that are likely involved in zoospore chemotaxis.
Functional Characterization of AasP, a Maturation Protease Autotransporter Protein ofActinobacillus pleuropneumoniae
Authors: Ali Tehmeena , Oldfield Neil J. , Wooldridge Karl G. , Turner David P. , Ala'Aldeen Dlawer A. A. 
Published: October 2008

ABSTRACTActinobacillus pleuropneumoniaeis the etiological agent of porcine pleuropneumonia, a highly contagious respiratory infection in pigs. AasP, a putative subtilisin-like serine protease autotransporter, has recently been identified inA. pleuropneumoniae. We hypothesized that, similarly to other autotransporters of this type, AasP may undergo autocatalytic cleavage resulting in release of the passenger domain of the protein. Furthermore, AasP may be responsible for cleavage of otherA. pleuropneumoniaeouter membrane proteins. To address these hypotheses, theaasPgene was cloned and the expressed recombinant AasP protein used to raise monospecific rabbit antiserum. Immunoblot analysis of whole-cell lysates and secreted proteins demonstrated that AasP does not undergo proteolytic cleavage. Immunoblot analysis also confirmed that AasP is universally expressed byA. pleuropneumoniae. Confirmation of the maturation protease function of AasP was obtained through phenotypic analysis of anA. pleuropneumoniae aasPdeletion mutant and by functional complementation. Comparison of the secreted proteins of the wild type, anaasPmutant derivative, and anaasPmutant complemented intransled to the identification of OmlA protein fragments that were present only in the secreted-protein preparations of the wild-type and complemented strains, indicating that AasP is involved in modification of OmlA. This is the first demonstration of a function for any autotransporter protein inActinobacillus pleuropneumoniae.
Mode of Expression and Functional Characterization of FCT-3 Pilus Region-Encoded Proteins in
Streptococcus pyogenes
Serotype M49
Authors: Nakata Masanobu , Köller Thomas , Moritz Karin , Ribardo Deborah , Jonas Ludwig , McIver Kevin S. , Sumitomo Tomoko , Terao Yutaka , Kawabata Shigetada , Podbielski Andreas , Kreikemeyer Bernd 
Published: October 2008

ABSTRACT

The human pathogen
Streptococcus pyogenes
(group A streptococcus [GAS]) pilus components, suggested to play a role in pathogenesis, are encoded in the variable FCT (fibronectin- and collagen-binding T-antigen) region. We investigated the functions of sortase A (SrtA), sortase C2 (SrtC2), and the FctA protein of the most prevalent type 3 FCT region from a serotype M49 strain. Although it is considered a housekeeping sortase, SrtA's activity is involved in pilus formation in addition to its essentiality for GAS extracellular matrix protein binding, host cell adherence/internalization, survival in human blood, and biofilm formation. SrtC2 activity is crucial for pilus formation but dispensable for the other phenotypes tested in vitro. FctA is the major pilus backbone protein, simultaneously acting as the M49 T antigen, and requires SrtC2 and LepA, a signal peptidase I homologue, for monomeric surface expression and polymerization, respectively. Collagen-binding protein Cpa expression supports pilus formation at the pilus base. Immunofluorescence microscopy and fluorescence-activated cell sorting analysis revealed several unexpected expression patterns, as follows: (i) the monomeric pilus protein FctA was found exclusively at the old poles of GAS cells, (ii) FctA protein expression increased with lower temperatures, and (iii) FctA protein expression was restricted to 20 to 50% of a given GAS M49 population, suggesting regulation by a bistability mode. Notably, disruption of pilus assembly by sortase deletion rendered GAS serotype M49 significantly more aggressive in a dermonecrotic mouse infection model, indicating that sortase activity and, consequently, pilus expression allow a subpopulation of this GAS serotype to be less aggressive. Thus, pilus expression may not be a virulence attribute of GAS per se.
Staphylococcus aureus
Elicits Marked Alterations in the Airway Proteome during Early Pneumonia
Authors: Ventura Christy L. , Higdon Roger , Hohmann Laura , Martin Daniel , Kolker Eugene , Liggitt H. Denny , Skerrett Shawn J. , Rubens Craig E. 
Published: October 2008

ABSTRACT

Pneumonia caused by
Staphylococcus aureus
is a growing concern in the health care community. We hypothesized that characterization of the early innate immune response to bacteria in the lungs would provide insight into the mechanisms used by the host to protect itself from infection. An adult mouse model of
Staphylococcus aureus
pneumonia was utilized to define the early events in the innate immune response and to assess the changes in the airway proteome during the first 6 h of pneumonia.
S. aureus
actively replicated in the lungs of mice inoculated intranasally under anesthesia to cause significant morbidity and mortality. By 6 h postinoculation, the release of proinflammatory cytokines caused effective recruitment of neutrophils to the airway. Neutrophil influx, loss of alveolar architecture, and consolidated pneumonia were observed histologically 6 h postinoculation. Bronchoalveolar lavage fluids from mice inoculated with phosphate-buffered saline (PBS) or
S. aureus
were depleted of overabundant proteins and subjected to strong cation exchange fractionation followed by liquid chromatography and tandem mass spectrometry to identify the proteins present in the airway. No significant changes in response to PBS inoculation or 30 min following
S. aureus
inoculation were observed. However, a dramatic increase in extracellular proteins was observed 6 h postinoculation with
S. aureus
, with the increase dominated by inflammatory and coagulation proteins. The data presented here provide a comprehensive evaluation of the rapid and vigorous innate immune response mounted in the host airway during the earliest stages of
S. aureus
pneumonia.
Role for the Chlamydial Type III Secretion Apparatus in Host Cytokine Expression
Authors: Prantner Daniel , Nagarajan Uma M. 
Published: October 2008

ABSTRACTIn many important human pathogens, such asShigellaandSalmonellaspp., the bacterial type III secretion (T3S) apparatus is required to initiate inflammation via activation of caspase-1- or NF-κB-dependent genes. Using an ex vivo infection model, the goal of the present study was to determine whether the chlamydial T3S apparatus also modulates the host inflammatory response. Infections of mouse peritoneal macrophages were performed withChlamydia muridarum, and the expression of inflammatory cytokines was monitored by quantitative reverse transcription-PCR and enzyme-linked immunosorbent assay. Since there is no current genetic system forChlamydiaspp., blockade of T3S was accomplished pharmacologically using a T3S inhibitor called INP0007. It has been previously shown that INP0007 also blocks chlamydial growth in vitro and that the addition of exogenous iron completely reverses this deficit. The addition of iron to INP0007-treatedC. muridarum-infected macrophages not only restored chlamydial growth deficit caused by INP0007 but also led to a multi-inclusion phenotype. Overall, T3S inhibition led to decreased interleukin-6 (IL-6), IL-1β, and CXCL10, whereas the tumor necrosis factor alpha levels were unchanged. Rescue of chlamydial growth by addition of iron sulfate did not restore cytokine production, implying that the decreased expression of many cytokines during infection was dependent on T3S and not solely on growth. In addition, the observation that the greatest effects of INP0007 were seen at late time points during infection suggests that a temporally regulated T3S effector protein(s) may be triggering the host cytokine response.
Factor H-Binding Protein Is Important for Meningococcal Survival in Human Whole Blood and Serum and in the Presence of the Antimicrobial Peptide LL-37
Authors: Seib K. L. , Serruto D. , Oriente F. , Delany I. , Adu-Bobie J. , Veggi D. , Aricò B. , Rappuoli R. , Pizza M. 
Published: October 2008

ABSTRACT

Factor H-binding protein (fHBP; GNA1870) is one of the antigens of the recombinant vaccine against serogroup B
Neisseria meningitidis
, which has been developed using reverse vaccinology and is the basis of a meningococcal B vaccine entering phase III clinical trials. Binding of factor H (fH), an inhibitor of the complement alternative pathway, to fHBP enables
N. meningitidis
to evade killing by the innate immune system. All fHBP null mutant strains analyzed were sensitive to killing in ex vivo human whole blood and serum models of meningococcal bacteremia with respect to the isogenic wild-type strains. The fHBP mutant strains of MC58 and BZ83 (high fHBP expressors) survived in human blood and serum for less than 60 min (decrease of >2 log
10
CFU), while NZ98/254 (intermediate fHBP expressor) and 67/00 (low fHBP expressor) showed decreases of >1 log
10
CFU after 60 to 120 min of incubation. In addition, fHBP is important for survival in the presence of the antimicrobial peptide LL-37 (decrease of >3 log
10
CFU after 2 h of incubation), most likely due to electrostatic interactions between fHBP and the cationic LL-37 molecule. Hence, the expression of fHBP by
N. meningitidis
strains is important for survival in human blood and human serum and in the presence of LL-37, even at low levels. The functional significance of fHBP in mediating resistance to the human immune response, in addition to its widespread distribution and its ability to induce bactericidal antibodies, indicates that it is an important component of the serogroup B meningococcal vaccine.
Pathogenic Potential of Emergent Sorbitol-Fermenting
Escherichia coli
O157:NM
Authors: Rosser Tracy , Dransfield Tracy , Allison Lesley , Hanson Mary , Holden Nicola , Evans Judith , Naylor Stuart , La Ragione Roberto , Low J. Christopher , Gally David L. 
Published: October 2008

ABSTRACT

Non-sorbitol-fermenting (NSF)
Escherichia coli
O157:H7 is the primary Shiga toxin-producing
E. coli
(STEC) serotype associated with human infection. Since 1988, sorbitol-fermenting (SF) STEC O157:NM strains have emerged and have been associated with a higher incidence of progression to hemolytic-uremic syndrome (HUS) than NSF STEC O157:H7. This study investigated bacterial factors that may account for the increased pathogenic potential of SF STEC O157:NM. While no evidence of toxin or toxin expression differences between the two O157 groups was found, the SF STEC O157:NM strains adhered at significantly higher levels to a human colonic cell line. Under the conditions tested, curli were shown to be the main factor responsible for the increased adherence to Caco-2 cells. Notably, 52 of 66 (79%) European SF STEC O157:NM strains tested bound Congo red at 37
ο
C and this correlated with curli expression. In a subset of strains, curli expression was due to increased expression from the
csgBAC
promoter that was not always a consequence of increased
csgD
expression. The capacity of SF STEC O157:NM strains to express curli at 37
ο
C may have relevance to the epidemiology of human infections as curliated strains could promote higher levels of colonization and inflammation in the human intestine. In turn, this could lead to increased toxin exposure and an increased likelihood of progression to HUS.
SMC Protein-Dependent Chromosome Condensation during Aerial Hyphal Development in
Streptomyces
Authors: Kois Agnieszka , Świątek Magdalena , Jakimowicz Dagmara , Zakrzewska-Czerwińska Jolanta 
Published: October 2008

ABSTRACT

Members of the SMC (
s
tructural
m
aintenance of
c
hromosomes) protein family play a central role in higher-order chromosome dynamics from bacteria to humans. So far, studies of bacterial SMC proteins have focused only on unicellular rod-shaped organisms that divide by binary fission. The conversion of multigenomic aerial hyphae of the mycelial organism
Streptomyces coelicolor
into chains of unigenomic spores requires the synchronous segregation of multiple chromosomes. Here we focus on the contribution of SMC proteins to sporulation-associated chromosome segregation in
S. coelicolor
. Deletion of the
smc
gene causes aberrant DNA condensation and missegregation of chromosomes (7.5% anucleate spores). In vegetative mycelium, immunostained SMC proteins were observed sporadically, while in aerial hyphae about to undergo sporulation they appeared as irregularly spaced foci which accompanied but did not colocalize with ParB complexes. Our data demonstrate that efficient chromosome segregation requires the joint action of SMC and ParB proteins. SMC proteins, similarly to ParAB and FtsZ, presumably belong to a larger group of proteins whose expression is highly induced in response to the requirement of aerial hyphal maturation.
A Novel Thermostable Arylesterase from the ArchaeonSulfolobus solfataricusP1: Purification, Characterization, and Expression
Authors: Park Young-Jun , Yoon Sung-Jin , Lee Hee-Bong 
Published: October 2008

ABSTRACTA novel thermostable arylesterase, a 35-kDa monomeric enzyme, was purified from the thermoacidophilic archaeonSulfolobus solfataricusP1. The optimum temperature and pH were 94°C and 7.0, respectively. The enzyme displayed remarkable thermostability: it retained 52% of its activity after 50 h of incubation at 90°C. In addition, the purified enzyme showed high stability against denaturing agents, including various detergents, urea, and organic solvents. The enzyme has broad substrate specificity besides showing an arylesterase activity toward aromatic esters: it exhibits not only carboxylesterase activity toward tributyrin andp-nitrophenyl esters containing unsubstituted fatty acids from butyrate (C4) to palmitate (C16), but also paraoxonase activity toward organophosphates such asp-nitrophenylphosphate, paraoxon, and methylparaoxon. Thekcat/Kmratios of the enzyme for phenyl acetate and paraoxon, the two most preferable substrates among all tested, were 30.6 and 119.4 s−1·μM−1, respectively. The arylesterase gene consists of 918 bp corresponding to 306 amino acid residues. The deduced amino acid sequence shares 34% identity with that of arylesterase fromAcinetobactersp. strain ADP1. Furthermore, we successfully expressed active recombinantS. solfataricusarylesterase inEscherichia coli. Together, our results show that the enzyme is a serine esterase belonging to the A-esterases and contains a catalytic triad composed of Ser156, Asp251, and His281 in the active site.
Comparative Genome Sequence Analysis of Multidrug-Resistant
Acinetobacter baumannii
Authors: Adams Mark D. , Goglin Karrie , Molyneaux Neil , Hujer Kristine M. , Lavender Heather , Jamison Jennifer J. , MacDonald Ian J. , Martin Kristienna M. , Russo Thomas , Campagnari Anthony A. , Hujer Andrea M. , Bonomo Robert A. , Gill Steven R. 
Published: October 2008

ABSTRACT

The recent emergence of multidrug resistance (MDR) in
Acinetobacter baumannii
has raised concern in health care settings worldwide. In order to understand the repertoire of resistance determinants and their organization and origins, we compared the genome sequences of three MDR and three drug-susceptible
A. baumannii
isolates. The entire MDR phenotype can be explained by the acquisition of discrete resistance determinants distributed throughout the genome. A comparison of closely related MDR and drug-susceptible isolates suggests that drug efflux may be a less significant contributor to resistance to certain classes of antibiotics than inactivation enzymes are. A resistance island with a variable composition of resistance determinants interspersed with transposons, integrons, and other mobile genetic elements is a significant but not universal contributor to the MDR phenotype. Four hundred seventy-five genes are shared among all six clinical isolates but absent from the related environmental species
Acinetobacter baylyi
ADP1. These genes are enriched for transcription factors and transporters and suggest physiological features of
A. baumannii
that are related to adaptation for growth in association with humans.
Biosynthesis of 7-Deazaguanosine-Modified tRNA Nucleosides: a New Role for GTP Cyclohydrolase I
Authors: Phillips Gabriella , El Yacoubi Basma , Lyons Benjamin , Alvarez Sophie , Iwata-Reuyl Dirk , de Crécy-Lagard Valérie 
Published: October 2008

ABSTRACT

Queuosine (Q) and archaeosine (G
+
) are hypermodified ribonucleosides found in tRNA. Q is present in the anticodon region of tRNA
GUN
in
Eukarya
and
Bacteria
, while G
+
is found at position 15 in the D-loop of archaeal tRNA. Prokaryotes produce these 7-deazaguanosine derivatives de novo from GTP through the 7-cyano-7-deazaguanine (pre-Q
0
) intermediate, but mammals import the free base, queuine, obtained from the diet or the intestinal flora. By combining the results of comparative genomic analysis with those of genetic studies, we show that the first enzyme of the folate pathway, GTP cyclohydrolase I (GCYH-I), encoded in
Escherichia coli
by
folE
, is also the first enzyme of pre-Q
0
biosynthesis in both prokaryotic kingdoms. Indeed, tRNA extracted from an
E. coli
Δ
folE
strain is devoid of Q and the deficiency is complemented by expressing GCYH-I-encoding genes from different bacterial or archaeal origins. In a similar fashion, tRNA extracted from a
Haloferax volcanii
strain carrying a deletion of the GCYH-I-encoding gene contains only traces of G
+
. These results link the production of a tRNA-modified base to primary metabolism and further clarify the biosynthetic pathway for these complex modified nucleosides.