bluuebunny/crossref_metadata_2025_split huggingface dataset:
LcrG-LcrV Interaction Is Required for Control of Yops Secretion in
Yersinia pestis
Authors: Matson Jyl S. , Nilles Matthew L. 
Published: July 2002

ABSTRACT

Yersinia pestis
expresses a set of plasmid-encoded virulence proteins called Yops and LcrV that are secreted and translocated into eukaryotic cells by a type III secretion system. LcrV is a multifunctional protein with antihost and positive regulatory effects on Yops secretion that forms a stable complex with a negative regulatory protein, LcrG. LcrG has been proposed to block the secretion apparatus (Ysc) from the cytoplasmic face of the inner membrane under nonpermissive conditions for Yops secretion, when levels of LcrV in the cell are low. A model has been proposed to describe secretion control based on the relative levels of LcrG and LcrV in the bacterial cytoplasm. This model proposes that under secretion-permissive conditions, levels of LcrV are increased relative to levels of LcrG, so that the excess LcrV titrates LcrG away from the Ysc, allowing secretion of Yops to occur. To further test this model, a mutant LcrG protein that could no longer interact with LcrV was created. Expression of this LcrG variant blocked secretion of Yops and LcrV under secretion permissive conditions in vitro and in a tissue culture model. These results agree with the previously described secretion-blocking activity of LcrG and demonstrate that the interaction of LcrV with LcrG is necessary for controlling Yops secretion.
DnaK Chaperone-Mediated Control of Activity of a ς
32
Homolog (RpoH) Plays a Major Role in the Heat Shock Response of
Agrobacterium tumefaciens
Authors: Nakahigashi Kenji , Yanagi Hideki , Yura Takashi 
Published: July 2002

ABSTRACT

RpoH (
Escherichia coli
ς
32
and its homologs) is the central regulator of the heat shock response in gram-negative proteobacteria. Here we studied salient regulatory features of RpoH in
Agrobacterium tumefaciens
by examining its synthesis, stability, and activity while increasing the temperature from 25 to 37°C. Heat induction of RpoH synthesis occurred at the level of transcription from an RpoH-dependent promoter, coordinately with that of DnaK, and followed by an increase in the RpoH level. Essentially normal induction of heat shock proteins was observed even with a strain that was unable to increase the RpoH level upon heat shock. Moreover, heat-induced accumulation of
dnaK
mRNA occurred without protein synthesis, showing that preexisting RpoH was sufficient for induction of the heat shock response. These results suggested that controlling the activity, rather than the amount, of RpoH plays a major role in regulation of the heat shock response. In addition, increasing or decreasing the DnaK-DnaJ chaperones specifically reduced or enhanced the RpoH activity, respectively. On the other hand, the RpoH protein was normally stable and remained stable during the induction phase but was destabilized transiently during the adaptation phase. We propose that the DnaK-mediated control of RpoH activity plays a primary role in the induction of heat shock response in
A. tumefaciens
, in contrast to what has been found in
E. coli
.
CotA of
Bacillus subtilis
Is a Copper-Dependent Laccase
Authors: Hullo Marie-Françoise , Moszer Ivan , Danchin Antoine , Martin-Verstraete Isabelle 
Published: July 2002

ABSTRACT

The spore coat protein CotA of
Bacillus subtilis
displays similarities with multicopper oxidases, including manganese oxidases and laccases.
B. subtilis
is able to oxidize manganese, but neither CotA nor other sporulation proteins are involved. We demonstrate that CotA is a laccase. Syringaldazine, a specific substrate of laccases, reacted with wild-type spores but not with Δ
cotA
spores. CotA may participate in the biosynthesis of the brown spore pigment, which appears to be a melanin-like product and to protect against UV light.
Promoter Specificity Elements in
Pseudomonas aeruginosa
Quorum-Sensing-Controlled Genes
Authors: Whiteley Marvin , Greenberg E. P. 
Published: July 2002

ABSTRACT

The LasR-dependent and RhlR-dependent quorum-sensing systems are global regulators of gene expression in
Pseudomonas aeruginosa
. Previous studies have demonstrated that promoter elements of the quorum-sensing-controlled genes
lasB
and
hcnABC
are important in density-dependent regulation. We have identified LasR- and RhlR-dependent determinants in promoters of quorum-sensing-controlled genes qsc102, qsc117 (
acpP
), and qsc131 (
phzA
to -
G
) by in silico, deletion, point-mutational, and primer extension analyses. Each of these genes (in addition to
lasI
and
rsaL
) is activated by LasR, and qsc117 and qsc131 also respond to RhlR. Point mutations in the promoters of the LasR-specific gene, qsc102, relax specificity so that this promoter can respond to RhlR in addition to LasR. Our findings indicate that quorum-sensing-controlled promoters in
P. aeruginosa
are either specific for LasR or respond to both LasR and RhlR and that critical bases in the promoter elements determine specificity.
Peptide Methionine Sulfoxide Reductase (MsrA) Is a Virulence Determinant in
Mycoplasma genitalium
Authors: Dhandayuthapani S. , Blaylock M. W. , Bebear C. M. , Rasmussen W. G. , Baseman J. B. 
Published: July 2002

ABSTRACT

Mycoplasma genitalium
is the smallest self-replicating microorganism and is implicated in human diseases, including urogenital and respiratory infections and arthritides.
M. genitalium
colonizes host cells primarily through adherence mechanisms mediated by a network of surface-associated membrane proteins, including adhesins and cytadherence-related proteins. In this paper, we show that cytadherence in
M. genitalium
is affected by an unrelated protein known as peptide methionine sulfoxide reductase (MsrA), an antioxidant repair enzyme that catalyzes the reduction of methionine sulfoxide [Met(O)] residues in proteins to methionine. An
msrA
disruption mutant of
M. genitalium
, constructed through homologous recombination, displayed markedly reduced adherence to sheep erythrocytes. In addition, the
msrA
mutant was incapable of growing in hamsters and exhibited hypersensitivity to hydrogen peroxide when compared to wild-type virulent
M. genitalium
. These results indicate that MsrA plays an important role in
M. genitalium
pathogenicity, possibly by protecting mycoplasma protein structures from oxidative damage or through alternate virulence-related pathways.
SdiA of
Salmonella enterica
Is a LuxR Homolog That Detects Mixed Microbial Communities
Authors: Michael Bindhu , Smith Jenee N. , Swift Simon , Heffron Fred , Ahmer Brian M. M. 
Published: July 2002

ABSTRACT

Proteins of the LuxR family detect the presence of
N
-acylhomoserine lactones (AHLs) and regulate transcription accordingly. When AHLs are synthesized by the same species that detects them, the system allows a bacterium to measure the population density of its own species, a phenomenon known as quorum sensing. The
sdiA
genes of
Escherichia coli
and
Salmonella enterica
serovar Typhimurium are predicted to encode LuxR homologs. However, these species do not appear to synthesize AHLs or any other molecule detected by SdiA. It has previously been demonstrated that overexpression of
sdiA
results in the activation of the
ftsQAZ
locus in
E. coli
and four other loci in
Salmonella
serovar Typhimurium. Here we report that transcriptional fusions to these five loci fall into two classes. The first class requires overexpression of
sdiA
for activation. The second class responds to
sdiA
expressed from its natural position in the chromosome if the appropriate AHLs are added to the culture. The only member of the second class is a series of P
rck-luxCDABE
fusions in
Salmonella
serovar Typhimurium. SdiA responds with highest sensitivity to AHLs that have a keto modification at the third carbon and an acyl chain length of 6 or 8 (half-maximal response between 1 and 5 nM). Growth of
Salmonella
in proximity to species known to synthesize these AHLs results in
sdiA
-dependent activation of the P
rck-luxCDABE
fusions. SdiA appears to be the first AHL receptor discovered that detects signals emanating exclusively from other species.
Evidence for Horizontal Transfer of
Ssu
DAT1I Restriction-Modification Genes to the
Streptococcus suis
Genome
Authors: Sekizaki Tsutomu , Otani Yoshiko , Osaki Makoto , Takamatsu Daisuke , Shimoji Yoshihiro 
Published: July 2002

ABSTRACT

Different strains of
Streptococcus suis
serotypes 1 and 2 isolated from pigs either contained a restriction-modification (R-M) system or lacked it. The R-M system was an isoschizomer of
Streptococcus pneumoniae Dpn
II, which recognizes nucleotide sequence 5′-GATC-3′. The nucleotide sequencing of the genes encoding the R-M system in
S. suis
DAT1, designated
Ssu
DAT1I, showed that the
Ssu
DAT1I gene region contained two methyltransferase genes, designated
ssuMA
and
ssuMB
, as does the
Dpn
II system. The deduced amino acid sequences of M.
Ssu
MA and M.
Ssu
MB showed 70 and 90% identity to M.
Dpn
II and M.
Dpn
A, respectively. However, the
Ssu
DAT1I system contained two isoschizomeric restriction endonuclease genes, designated
ssuRA
and
ssuRB
. The deduced amino acid sequence of R.
Ssu
RA was 49% identical to that of R.
Dpn
II, and R.
Ssu
RB was 72% identical to R.
Lla
DCHI of
Lactococcus lactis
subsp.
cremoris
DCH-4. The four
Ssu
DAT1I genes overlapped and were bounded by purine biosynthetic gene clusters in the following gene order:
purF-purM-purN-purH-ssuMA-ssuMB-ssuRA-ssuRB-purD-purE
. The G+C content of the
Ssu
DAT1I gene region (34.1%) was lower than that of the
pur
region (48.9%), suggesting horizontal transfer of the
Ssu
DAT1I system. No transposable element or long-repeat sequence was found in the flanking regions. The
Ssu
DAT1I genes were functional by themselves, as they were individually expressed in
Escherichia coli
. Comparison of the sequences between strains with and without the R-M system showed that only the region from 53 bp upstream of
ssuMA
to 5 bp downstream of
ssuRB
was inserted in the intergenic sequence between
purH
and
purD
and that the insertion target site was not the recognition site of
Ssu
DAT1I. No notable substitutions or insertions could be found, and the structures were conserved among all the strains. These results suggest that the
Ssu
DAT1I system could have been integrated into the
S. suis
chromosome by an illegitimate recombination mechanism.
Transcription ofnhaA, the Main Na+/H+Antiporter ofEscherichia coli, Is Regulated by Na+and Growth Phase
Authors: Dover Nir , Padan Etana 
Published: July 2002

ABSTRACTThe transcription ofnhaA, encoding the main Na+/H+antiporter ofEscherichia coli,is induced by Na+, regulated by NhaR, and affected by H-NS. In this work the roles of the twonhaApromoters (P1 and P2) were studied by analysis of transcription both in vivo and in vitro and promoter mutations. We found that P1 is an NhaR-dependent, Na+-induced, and H-NS-affected promoter both in the exponential and stationary phases. An in vitro transcription assay demonstrated that P1 is activated by ς70-RNA polymerase and both NhaR and H-NS increase the specificity of P1. Remarkably, in marked contrast to P1, P2 exhibits very low activity during the exponential phase but is induced in the stationary phase to become the major promoter. Furthermore, P2 is activated by ςSand is neither induced by Na+nor dependent on NhaR or affected by H-NS. Hence, this work establishes thatnhaAhas a dual mode of regulation, each involving a different promoter, and reveals that P2 and ςStogether are responsible for the survival of stationary-phase cells in the presence of high Na+, alkaline pH, and the combination of high Na+and alkaline pH, the most stressful condition.
Acetate and Formate Stress: Opposite Responses in the Proteome of
Escherichia coli
Authors: Kirkpatrick Christopher , Maurer Lisa M. , Oyelakin Nikki E. , Yoncheva Yuliya N. , Maurer Russell , Slonczewski Joan L. 
Published: July 2002

ABSTRACT

Acetate and formate are major fermentation products of
Escherichia coli
. Below pH 7, the balance shifts to lactate; an oversupply of acetate or formate retards growth.
E. coli
W3110 was grown with aeration in potassium-modified Luria broth buffered at pH 6.7 in the presence or absence of added acetate or formate, and the protein profiles were compared by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Acetate increased the steady-state expression levels of 37 proteins, including periplasmic transporters for amino acids and peptides (ArtI, FliY, OppA, and ProX), metabolic enzymes (YfiD and GatY), the RpoS growth phase regulon, and the autoinducer synthesis protein LuxS. Acetate repressed 17 proteins, among them phosphotransferase (Pta). An
ackA-pta
deletion, which nearly eliminates interconversion between acetate and acetyl-coenzyme A (acetyl-CoA), led to elevated basal levels of 16 of the acetate-inducible proteins, including the RpoS regulon. Consistent with RpoS activation, the
ackA-pta
strain also showed constitutive extreme-acid resistance. Formate, however, repressed 10 of the acetate-inducible proteins, including the RpoS regulon. Ten of the proteins with elevated basal levels in the
ackA-pta
strain were repressed by growth of the mutant with formate; thus, the formate response took precedence over the loss of the
ackA-pta
pathway. The similar effects of exogenous acetate and the
ackA-pta
deletion, and the opposite effect of formate, could have several causes; one possibility is that the excess buildup of acetyl-CoA upregulates stress proteins but excess formate depletes acetyl-CoA and downregulates these proteins.
The Dimerization Function of MinC Resides in a Structurally Autonomous C-Terminal Domain
Authors: Szeto Tim H. , Rowland Susan L. , King Glenn F. 
Published: July 2002

ABSTRACT

Limited proteolysis of the
Escherichia coli
cell division inhibitor MinC reveals that its dimerization function resides in a structurally autonomous C-terminal domain. We show that cytoplasmic MinC is poised near the monomer-dimer equilibrium and propose that it only becomes entirely dimeric once recruited to the membrane by MinD.
Comprehensive DNA Microarray Analysis of
Bacillus subtilis
Two-Component Regulatory Systems
Authors: Kobayashi Kazuo , Ogura Mitsuo , Yamaguchi Hirotake , Yoshida Ken-Ichi , Ogasawara Naotake , Tanaka Teruo , Fujita Yasutaro 
Published: July 2002

ABSTRACT

It has recently been shown through DNA microarray analysis of
Bacillus subtilis
two-component regulatory systems (DegS-DegU, ComP-ComA, and PhoR-PhoP) that overproduction of a response regulator of the two-component systems in the background of a deficiency of its cognate sensor kinase affects the regulation of genes, including its target ones. The genome-wide effect on gene expression caused by the overproduction was revealed by DNA microarray analysis. In the present work, we newly analyzed 24 two-component systems by means of this strategy, leaving out 8 systems to which it was unlikely to be applicable. This analysis revealed various target gene candidates for these two-component systems. It is especially notable that interesting interactions appeared to take place between several two-component systems. Moreover, the probable functions of some unknown two-component systems were deduced from the list of their target gene candidates. This work is heuristic but provides valuable information for further study toward a comprehensive understanding of the
B. subtilis
two-component regulatory systems. The DNA microarray data obtained in this work are available at the KEGG Expression Database website (
http://www.genome.ad.jp/kegg/expression
).
Effect of Sequences of the Active-Site Dipeptides of DsbA and DsbC on In Vivo Folding of Multidisulfide Proteins in
Escherichia coli
Authors: Bessette Paul H. , Qiu Ji , Bardwell James C. A. , Swartz James R. , Georgiou George 
Published: July 2002

ABSTRACT

We have examined the role of the active-site CXXC central dipeptides of DsbA and DsbC in disulfide bond formation and isomerization in the
Escherichia coli
periplasm. DsbA active-site mutants with a wide range of redox potentials were expressed either from the
trc
promoter on a multicopy plasmid or from the endogenous
dsbA
promoter by integration of the respective alleles into the bacterial chromosome. The
dsbA
alleles gave significant differences in the yield of active murine urokinase, a protein containing 12 disulfides, including some that significantly enhanced urokinase expression over that allowed by wild-type DsbA. No direct correlation between the in vitro redox potential of
dsbA
variants and the urokinase yield was observed. These results suggest that the active-site CXXC motif of DsbA can play an important role in determining the folding of multidisulfide proteins, in a way that is independent from DsbA's redox potential. However, under aerobic conditions, there was no significant difference among the DsbA mutants with respect to phenotypes depending on the oxidation of proteins with few disulfide bonds. The effect of active-site mutations in the CXXC motif of DsbC on disulfide isomerization in vivo was also examined. A library of DsbC expression plasmids with the active-site dipeptide randomized was screened for mutants that have increased disulfide isomerization activity. A number of DsbC mutants that showed enhanced expression of a variant of human tissue plasminogen activator as well as mouse urokinase were obtained. These DsbC mutants overwhelmingly contained an aromatic residue at the C-terminal position of the dipeptide, whereas the N-terminal residue was more diverse. Collectively, these data indicate that the active sites of the soluble thiol- disulfide oxidoreductases can be modulated to enhance disulfide isomerization and protein folding in the bacterial periplasmic space.
Inhibition of
Escherichia coli
Acetyl Coenzyme A Carboxylase by Acyl-Acyl Carrier Protein
Authors: Davis Mark S. , Cronan John E. 
Published: July 2002

ABSTRACT

Escherichia coli
acetyl coenzyme A carboxylase (ACC), the first enzyme of the fatty acid biosynthetic pathway, is inhibited by acylated derivatives of acyl carrier protein (ACP). ACP lacking an acyl moiety does not inhibit ACC. Acylated derivatives of ACP having chain lengths of 6 to 20 carbon atoms were similarly inhibitory at physiologically relevant concentrations. The observed feedback inhibition was specific to the protein moiety, as shown by the inability of the palmitoyl thioester of spinach ACP I to inhibit ACC.
VpsR, a Member of the Response Regulators of the Two-Component Regulatory Systems, Is Required for Expression of
vps
Biosynthesis Genes and EPS
ETr
-Associated Phenotypes in
Vibrio cholerae
O1 El Tor
Authors: Yildiz Fitnat H. , Dolganov Nadia A. , Schoolnik Gary K. 
Published: July 2002

ABSTRACT

The rugose colonial variant of
Vibrio cholerae
O1 El Tor produces an exopolysaccharide (EPS
ETr
) that enables the organism to form a biofilm and to resist oxidative stress and the bactericidal action of chlorine. Transposon mutagenesis of the rugose variant led to the identification of
vpsR
, which codes for a homologue of the NtrC subclass of response regulators. Targeted disruption of
vpsR
in the rugose colony genetic background yielded a nonreverting smooth-colony morphotype that produced no detectable EPS
ETr
and did not form an architecturally mature biofilm. Analysis of two genes,
vpsA
and
vpsL
, within the
vps
cluster of EPS
ETr
biosynthesis genes revealed that their expression is induced above basal levels in the rugose variant, compared to the smooth colonial variant, and requires
vpsR
. These results show that VpsR functions as a positive regulator of
vpsA
and
vpsL
and thus acts to positively regulate EPS
ETr
production and biofilm formation.
Analysis of
cis-
and
trans-
Acting Factors Involved in Regulation of the
Streptococcus mutans
Fructanase Gene (
fruA
)
Authors: Wen Zezhang T. , Burne Robert A. 
Published: July 2002

ABSTRACT

There are two primary levels of control of the expression of the fructanase gene (
fruA
) of
Streptococcus mutans
: induction by levan, inulin, or sucrose and repression in the presence of glucose and other readily metabolized sugars. The goals of this study were to assess the functionality of putative
cis-
acting regulatory elements and to begin to identify the
trans
-acting factors involved in induction and catabolite repression of
fruA.
The
fruA
promoter and its derivatives generated by deletions and/or site-directed mutagenesis were fused to a promoterless chloramphenicol acetyltransferase (CAT) gene as a reporter, and strains carrying the transcriptional fusions were then analyzed for CAT activities in response to growth on various carbon sources. A dyadic sequence, ATGACA(TC)TGTCAT, located at −72 to −59 relative to the transcription initiation site was shown to be essential for expression of
fruA
. Inactivation of the genes that encode fructose-specific enzymes II resulted in elevated expression from the
fruA
promoter, suggesting negative regulation of
fruA
expression by the fructose phosphotransferase system. Mutagenesis of a terminator-like structure located in the 165-base 5′ untranslated region of the
fruA
mRNA or insertional inactivation of antiterminator genes revealed that antitermination was not a mechanism controlling induction or repression of
fruA
, although the untranslated leader mRNA may play a role in optimal expression of fructanase. Deletion or mutation of a consensus catabolite response element alleviated glucose repression of
fruA
, but interestingly, inactivation of the
ccpA
gene had no discernible effect on catabolite repression of
fruA
. Accumulating data suggest that expression of
fruA
is regulated by a mechanism that has several unique features that distinguish it from archetypical polysaccharide catabolic operons of other gram-positive bacteria.
Plasmid-Encoded Autolysin inBacillus anthracis: Modular Structure and Catalytic Properties
Authors: Mesnage Stéphane , Fouet Agnès 
Published: July 2002

ABSTRACTABacillus anthracisvirulence plasmid-encoded peptidoglycan hydrolase (AmiA) with sequence similarity toN-acetylmuramoyl-l-alanine amidases hydrolyzes peptidoglycan independently of cell wall binding. Residues H341, E355, H415, and E486 are absolutely required for catalysis. Many AmiA paralogs are fused to different sorting signals, suggesting that these modular proteins result from domain shuffling.
Heterologous Production of
Clostridium cellulovorans engB
, Using Protease-Deficient
Bacillus subtilis
, and Preparation of Active Recombinant Cellulosomes
Authors: Murashima Koichiro , Chen Chyi-Liang , Kosugi Akihiko , Tamaru Yutaka , Doi Roy H. , Wong Sui-Lam 
Published: July 2002

ABSTRACT

In cellulosomes produced by
Clostridium
spp., the high-affinity interaction between the dockerin domain and the cohesin domain is responsible for the assembly of enzymatic subunits into the complex. Thus, heterologous expression of full-length enzymatic subunits containing the dockerin domains and of the scaffolding unit is essential for the in vitro assembly of a “designer” cellulosome, or a recombinant cellulosome with a specific function. We report the preparation of
Clostridium cellulovorans
recombinant cellulosomes containing the enzymatic subunit EngB and the scaffolding unit, mini-CbpA, containing a cellulose binding domain, a putative cell wall binding domain, and two cohesin units. The full-length EngB containing the dockerin domain was expressed by
Bacillus subtilis
WB800, which is deficient in eight extracellular proteases, to prevent the proteolytic cleavage of the enzymatic subunit between the catalytic and dockerin domains that was observed in previous attempts to express EngB with
Escherichia coli
. The assembly of recombinant EngB with the mini-CbpA was confirmed by immunostaining, a cellulose binding experiment, and native polyacrylamide gel electrophoresis analysis.