scholarly journals Diverse Genetic Regulon of the Virulence-Associated Transcriptional Regulator MucR in Brucella abortus 2308

2013 ◽  
Vol 81 (4) ◽  
pp. 1040-1051 ◽  
Author(s):  
Clayton C. Caswell ◽  
Ahmed E. M. Elhassanny ◽  
Emilie E. Planchin ◽  
Christelle M. Roux ◽  
Jenni N. Weeks-Gorospe ◽  
...  
Keyword(s):  
Brucella Abortus ◽  
Iron Homeostasis ◽  
Brucella Melitensis ◽  
Cell Envelope ◽  
Transcriptional Regulator ◽  
Growth Defect ◽  
Mobility Shift ◽  
Content Type ◽  
Polysaccharide Biosynthesis

ABSTRACTThe Ros-type regulator MucR is one of the few transcriptional regulators that have been linked to virulence inBrucella. Here, we show that aBrucella abortusin-framemucRdeletion strain exhibits a pronounced growth defect duringin vitrocultivation and, more importantly, that themucRmutant is attenuated in cultured macrophages and in mice. The genetic basis for the attenuation ofBrucella mucRmutants has not been defined previously, but in the present study the genes regulated by MucR inB. abortushave been elucidated using microarray analysis and real-time reverse transcription-PCR (RT-PCR). InB. abortus2308, MucR regulates a wide variety of genes whose products may function in establishing and maintaining cell envelope integrity, polysaccharide biosynthesis, iron homeostasis, genome plasticity, and transcriptional regulation. Particularly notable among the MucR-regulated genes identified isarsR6(nolR), which encodes a transcriptional regulator previously linked to virulence inBrucella melitensis16 M. Importantly, electrophoretic mobility shift assays (EMSAs) determined that a recombinant MucR protein binds directly to the promoter regions of several genes repressed by MucR (includingarsR6[nolR]), and inBrucella, as in other alphaproteobacteria, MucR binds to its own promoter to repress expression of the gene that encodes it. Overall, these studies have uncovered the diverse genetic regulon of MucR inBrucella, and in doing so this work has begun to define the MucR-controlled genetic circuitry whose misregulation contributes to the virulence defect ofBrucella mucRmutants.

scholarly journals A MarR-Type Regulator Directly Activates Transcription from the Brucella abortus virB Promoter by Sharing a Redundant Role with HutC

2012 ◽  
Vol 194 (23) ◽  
pp. 6431-6440 ◽  
Author(s):  
Rodrigo Sieira ◽  
Gastón M. Arocena ◽  
Angeles Zorreguieta ◽  
Diego J. Comerci ◽  
Rodolfo A. Ugalde
Keyword(s):  
Transcription Factors ◽  
Dna Sequences ◽  
Cell Envelope ◽  
Regulatory Element ◽  
Dependent Manner ◽  
Secretion Systems ◽  
Mobility Shift ◽  
Content Type ◽  
Environmental Signals

ABSTRACTType IV secretion systems (T4SS) are multiprotein structures that direct the translocation of specific molecules across the bacterial cell envelope. As in other bacteria, pathogenicity of the genusBrucellaessentially depends on the integrity of the T4SS-encodingvirBoperon, whose expression is regulated by multiple transcription factors belonging to different families. Previously, we identified IHF and HutC, two direct regulators of thevirBgenes that were isolated from total protein extracts ofBrucella. Here, we report the identification of MdrA, a third regulatory element that was isolated using the same screening procedure. This transcription factor, which belongs to the MarR-family of transcriptional regulators, binds at two different sites of thevirBpromoter and regulates expression in a growth phase-dependent manner. Like other members of the MarR family, specific ligands were able to dissociate MdrA from DNAin vitro. Determination of the MdrA-binding sites by DNase I footprinting and analyses of protein-DNA complexes by electrophoresis mobility shift assays (EMSAs) showed that MdrA competes with IHF and HutC for the binding to the promoter because their target DNA sequences overlap. Unlike IHF, both MdrA and HutC bound to the promoter without inducing bending of DNA. Moreover, the two latter transcription factors activatedvirBexpression to similar extents, and in doing so, they are functionally redundant. Taken together, our results show that MdrA is a regulatory element that directly modulates the activity of thevirBpromoter and is probably involved in coordinating gene expression in response to specific environmental signals.

scholarly journals The LysR-Type Transcriptional Regulator CrgA Negatively Regulates the Flagellar Master Regulator flhDC in Ralstonia solanacearum GMI1000

2020 ◽  
Vol 203 (1) ◽  
Author(s):  
Xiaojing Fan ◽  
Zhiwen Zhao ◽  
Tingyan Sun ◽  
Wei Rou ◽  
Caiying Gui ◽  
...  
Keyword(s):  
Cell Motility ◽  
Ralstonia Solanacearum ◽  
Host Plants ◽  
Transcriptional Regulator ◽  
Growth Defect ◽  
Wild Type ◽  
Mobility Shift ◽  
Content Type ◽  
Gus Reporter ◽  
Electrophoretic Mobility Shift Assays

ABSTRACT The invasion and colonization of host plants by the destructive pathogen Ralstonia solanacearum rely on its cell motility, which is controlled by multiple factors. Here, we report that the LysR-type transcriptional regulator CrgA (RS_RS16695) represses cell motility in R. solanacearum GMI1000. CrgA possesses common features of a LysR-type transcriptional regulator and contains an N-terminal helix-turn-helix motif as well as a C-terminal LysR substrate-binding domain. Deletion of crgA results in an enhanced swim ring and increased transcription of flhDC. In addition, the ΔcrgA mutant possesses more polar flagella than wild-type GMI1000 and exhibits higher expression of the flagellin gene fliC. Despite these alterations, the ΔcrgA mutant did not have a detectable growth defect in culture. Yeast one-hybrid and electrophoretic mobility shift assays revealed that CrgA interacts directly with the flhDC promoter. Expressing the β-glucuronidase (GUS) reporter under the control of the crgA promoter showed that crgA transcription is dependent on cell density. Soil-soaking inoculation with the crgA mutant caused wilt symptoms on tomato (Solanum lycopersicum L. cv. Hong yangli) plants earlier than inoculation with the wild-type GMI1000 but resulted in lower disease severity. We conclude that the R. solanacearum regulator CrgA represses flhDC expression and consequently affects the expression of fliC to modulate cell motility, thereby conditioning disease development in host plants. IMPORTANCE Ralstonia solanacearum is a widely distributed soilborne plant pathogen that causes bacterial wilt disease on diverse plant species. Motility is a critical virulence attribute of R. solanacearum because it allows this pathogen to efficiently invade and colonize host plants. In R. solanacearum, motility-defective strains are markedly affected in pathogenicity, which is coregulated with multiple virulence factors. In this study, we identified a new LysR-type transcriptional regulator (LTTR), CrgA, that negatively regulates motility. The mutation of the corresponding gene leads to the precocious appearance of wilt symptoms on tomato plants when the pathogen is introduced using soil-soaking inoculation. This study indicates that the regulation of R. solanacearum motility is more complex than previously thought and enhances our understanding of flagellum regulation in R. solanacearum.

scholarly journals Characterization of the Organic Hydroperoxide Resistance System of Brucella abortus 2308

2012 ◽  
Vol 194 (18) ◽  
pp. 5065-5072 ◽  
Author(s):  
Clayton C. Caswell ◽  
John E. Baumgartner ◽  
Daniel W. Martin ◽  
R. Martin Roop
Keyword(s):  
Brucella Abortus ◽  
Sequence Similarity ◽  
Mobility Shift ◽  
Organic Hydroperoxide ◽  
Content Type ◽  
Dnase I Footprinting ◽  
Organic Hydroperoxides ◽  
Electrophoretic Mobility Shift Assays

ABSTRACTThe organic hydroperoxide resistance protein Ohr has been identified in numerous bacteria where it functions in the detoxification of organic hydroperoxides, and expression ofohris often regulated by a MarR-type regulator called OhrR. The genes annotated as BAB2_0350 and BAB2_0351 in theBrucella abortus2308 genome sequence are predicted to encode OhrR and Ohr orthologs, respectively. Using isogenicohrandohrRmutants andlacZpromoter fusions, it was determined that Ohr contributes to resistance to organic hydroperoxide, but not hydrogen peroxide, inB. abortus2308 and that OhrR represses the transcription of bothohrandohrRin this strain. Moreover, electrophoretic mobility shift assays and DNase I footprinting revealed that OhrR binds directly to a specific region in the intergenic region betweenohrandohrRthat shares extensive nucleotide sequence similarity with so-called “OhrR boxes” described in other bacteria. While Ohr plays a prominent role in protectingB. abortus2308 from organic hydroperoxide stress inin vitroassays, this protein is not required for the wild-type virulence of this strain in cultured murine macrophages or experimentally infected mice.

scholarly journals Arsenic Directly Binds to and Activates the Yeast AP-1-Like Transcription Factor Yap8

2015 ◽  
Vol 36 (6) ◽  
pp. 913-922 ◽  
Author(s):  
Nallani Vijay Kumar ◽  
Jianbo Yang ◽  
Jitesh K. Pillai ◽  
Swati Rawat ◽  
Carlos Solano ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transcriptional Activation ◽  
Transcriptional Response ◽  
Transcriptional Regulator ◽  
Yeast Protein ◽  
Content Type ◽  
Arsenic Tolerance ◽  
Arsenic Sensing

The AP-1-like transcription factor Yap8 is critical for arsenic tolerance in the yeastSaccharomyces cerevisiae. However, the mechanism by which Yap8 senses the presence of arsenic and activates transcription of detoxification genes is unknown. Here we demonstrate that Yap8 directly binds to trivalent arsenite [As(III)]in vitroandin vivoand that approximately one As(III) molecule is bound per molecule of Yap8. As(III) is coordinated by three sulfur atoms in purified Yap8, and our genetic and biochemical data identify the cysteine residues that form the binding site as Cys132, Cys137, and Cys274. As(III) binding by Yap8 does not require an additional yeast protein, and Yap8 is regulated neither at the level of localization nor at the level of DNA binding. Instead, our data are consistent with a model in which a DNA-bound form of Yap8 acts directly as an As(III) sensor. Binding of As(III) to Yap8 triggers a conformational change that in turn brings about a transcriptional response. Thus, As(III) binding to Yap8 acts as a molecular switch that converts inactive Yap8 into an active transcriptional regulator. This is the first report to demonstrate how a eukaryotic protein couples arsenic sensing to transcriptional activation.

scholarly journals The Transcriptional Regulator CpsY Is Important for Innate Immune Evasion in Streptococcus pyogenes

2016 ◽  
Vol 85 (3) ◽  
Author(s):  
Luis A. Vega ◽  
Kayla M. Valdes ◽  
Ganesh S. Sundar ◽  
Ashton T. Belew ◽  
Emrul Islam ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Immune Evasion ◽  
Immune Cell ◽  
Group A Streptococcus ◽  
Transcriptional Regulator ◽  
Innate Immune ◽  
Content Type ◽  
Human Host

ABSTRACTAs an exclusively human pathogen,Streptococcus pyogenes(the group A streptococcus [GAS]) has specifically adapted to evade host innate immunity and survive in multiple tissue niches, including blood. GAS can overcome the metabolic constraints of the blood environment and expresses various immunomodulatory factors necessary for survival and immune cell resistance. Here we present our investigation of one such factor, the predicted LysR family transcriptional regulator CpsY. The encoding gene,cpsY, was initially identified as being required for GAS survival in a transposon-site hybridization (TraSH) screen in whole human blood. CpsY is homologous with transcriptional regulators ofStreptococcus mutans(MetR),Streptococcus iniae(CpsY), andStreptococcus agalactiae(MtaR) that regulate methionine transport, amino acid metabolism, resistance to neutrophil-mediated killing, and survivalin vivo. Our investigation indicated that CpsY is involved in GAS resistance to innate immune cells of its human host. However, GAS CpsY does not manifest thein vitrophenotypes of its homologs in other streptococcal species. GAS CpsY appears to regulate a small set of genes that is markedly different from the regulons of its homologs. The differential expression of these genes depends on the growth medium, and CpsY modestly influences their expression. The GAS CpsY regulon includes known virulence factors (mntE,speB,spd,nga[spn],prtS[SpyCEP], andsse) and cell surface-associated factors of GAS (emm1,mur1.2,sibA[cdhA], andM5005_Spy0500). Intriguingly, the loss of CpsY in GAS does not result in virulence defects in murine models of infection, suggesting that CpsY function in immune evasion is specific to the human host.

scholarly journals Production of the Siderophore 2,3-Dihydroxybenzoic Acid Is Required for Wild-Type Growth of Brucella abortus in the Presence of Erythritol under Low-Iron Conditions In Vitro

2003 ◽  
Vol 71 (5) ◽  
pp. 2927-2832 ◽  
Author(s):  
Bryan H. Bellaire ◽  
Philip H. Elzer ◽  
Cynthia L. Baldwin ◽  
R. Martin Roop
Keyword(s):  
Brucella Abortus ◽  
Reproductive Tract ◽  
Iron Acquisition ◽  
Energy Sources ◽  
Growth Defect ◽  
Wild Type ◽  
Dihydroxybenzoic Acid ◽  
Experimental Findings ◽  
The Relationship

ABSTRACT Production of the siderophore 2,3-dihyroxybenzoic acid (2,3-DHBA) is required for the wild-type virulence of Brucella abortus in cattle. A possible explanation for this requirement was uncovered when it was determined that a B. abortus dhbC mutant (BHB1) defective in 2,3-DHBA production displays marked growth restriction in comparison to its parent strain, B. abortus 2308, when cultured in the presence of erythritol under low-iron conditions. This phenotype is not displayed when these strains are cultured under low-iron conditions in the presence of other readily utilizable carbon and energy sources. The addition of either exogenous 2,3-DHBA or FeCl3 relieves this growth defect, suggesting that the inability of the B. abortus dhbC mutant to display wild-type growth in the presence of erythritol under iron-limiting conditions is due to a defect in iron acquisition. Restoring 2,3-DHBA production to the B. abortus dhbC mutant by genetic complementation abolished the erythritol-specific growth defect exhibited by this strain in low-iron medium, verifying the relationship between 2,3-DHBA production and efficient growth in the presence of erythritol under low-iron conditions. The positive correlation between 2,3-DHBA production and growth in the presence of erythritol was further substantiated by the observation that the addition of erythritol to low-iron cultures of B. abortus 2308 stimulated the production of 2,3-DHBA by increasing the transcription of the dhbCEBA operon. Correspondingly, the level of exogenous iron needed to repress dhbCEBA expression in B. abortus 2308 was also greater when this strain was cultured in the presence of erythritol than that required when it was cultured in the presence of any of the other readily utilizable carbon and energy sources tested. The tissues of the bovine reproductive tract are rich in erythritol during the latter stages of pregnancy, and the ability to metabolize erythritol is thought to be important to the virulence of B. abortus in pregnant ruminants. Consequently, the experimental findings presented here offer a plausible explanation for the attenuation of the B. abortus 2,3-DHBA-deficient mutant BHB1 in pregnant ruminants.

scholarly journals Protection of BALB/c Mice against Brucella abortus 544 Challenge by Vaccination with Bacterioferritin or P39 Recombinant Proteins with CpG Oligodeoxynucleotides as Adjuvant

2001 ◽  
Vol 69 (8) ◽  
pp. 4816-4822 ◽  
Author(s):  
Ayman Al-Mariri ◽  
Anne Tibor ◽  
Pascal Mertens ◽  
Xavier De Bolle ◽  
Patrick Michel ◽  
...  
Keyword(s):  
Recombinant Proteins ◽  
Brucella Abortus ◽  
Mononuclear Cells ◽  
Brucella Melitensis ◽  
Cpg Odn ◽  
Peripheral Blood Mononuclear ◽  
Recombinant Antigens ◽  
Cpg Oligodeoxynucleotides ◽  
Ifn Γ

ABSTRACT The P39 and the bacterioferrin (BFR) antigens of Brucella melitensis 16M were previously identified as T dominant antigens able to induce both delayed-type hypersensivity in sensitized guinea pigs and in vitro gamma interferon (IFN-γ) production by peripheral blood mononuclear cells from infected cattle. Here, we analyzed the potential for these antigens to function as a subunitary vaccine against Brucella abortus infection in BALB/c mice, and we characterized the humoral and cellular immune responses induced. Mice were injected with each of the recombinant proteins alone or adjuvanted with either CpG oligodeoxynucleotides (CpG ODN) or non-CpG ODN. Mice immunized with the recombinant antigens with CpG ODN were the only group demonstrating both significant IFN-γ production and T-cell proliferation in response to either Brucella extract or to the respective antigen. The same conclusion holds true for the antibody response, which was only demonstrated in mice immunized with recombinant antigens mixed with CpG ODN. The antibody titers (both immunoglobulin G1 [IgG1] and IgG2a) induced by P39 immunization were higher than the titers induced by BFR (only IgG2a). Using a B. abortus 544 challenge, the level of protection was analyzed and compared to the protection conferred by one immunization with the vaccine strain B19. Immunization with P39 and CpG ODN gave a level of protection comparable to the one conferred by B19 at 4 weeks postchallenge, and the mice were still significantly protected at 8 weeks postchallenge, although to a lesser extent than the B19-vaccinated group. Intriguingly, no protection was detected after BFR vaccination. All other groups did not demonstrate any protection.

scholarly journals Genetic regulation, biochemical properties and physiological importance of arginase from Sinorhizobium meliloti

Microbiology ◽  
2020 ◽  
Vol 166 (5) ◽  
pp. 484-497 ◽  
Author(s):  
Alejandra Arteaga Ide ◽  
Victor M. Hernández ◽  
Liliana Medina-Aparicio ◽  
Edson Carcamo-Noriega ◽  
Lourdes Girard ◽  
...  
Keyword(s):  
Type Species ◽  
Sinorhizobium Meliloti ◽  
Arginase Activity ◽  
Wild Type ◽  
Mobility Shift ◽  
Content Type ◽  
Link Type ◽  
Arginine Catabolism

In bacteria, l-arginine is a precursor of various metabolites and can serve as a source of carbon and/or nitrogen. Arginine catabolism by arginase, which hydrolyzes arginine to l-ornithine and urea, is common in nature but has not been studied in symbiotic nitrogen-fixing rhizobia. The genome of the alfalfa microsymbiont Sinorhizobium meliloti 1021 has two genes annotated as arginases, argI1 (smc03091) and argI2 (sma1711). Biochemical assays with purified ArgI1 and ArgI2 (as 6His-Sumo-tagged proteins) showed that only ArgI1 had detectable arginase activity. A 1021 argI1 null mutant lacked arginase activity and grew at a drastically reduced rate with arginine as sole nitrogen source. Wild-type growth and arginase activity were restored in the argI1 mutant genetically complemented with a genomically integrated argI1 gene. In the wild-type, arginase activity and argI1 transcription were induced several fold by exogenous arginine. ArgI1 purified as a 6His-Sumo-tagged protein had its highest in vitro enzymatic activity at pH 7.5 with Ni2+ as cofactor. The enzyme was also active with Mn2+ and Co2+, both of which gave the enzyme the highest activities at a more alkaline pH. The 6His-Sumo-ArgI1 comprised three identical subunits based on the migration of the urea-dissociated protein in a native polyacrylamide gel. A Lrp-like regulator (smc03092) divergently transcribed from argI1 was required for arginase induction by arginine or ornithine. This regulator was designated ArgIR. Electrophoretic mobility shift assays showed that purified ArgIR bound to the argI1 promoter in a region preceding the predicted argI1 transcriptional start. Our results indicate that ArgI1 is the sole arginase in S. meliloti , that it contributes substantially to arginine catabolism in vivo and that argI1 induction by arginine is dependent on ArgIR.

scholarly journals How the Anaerobic Enteropathogen Clostridioides difficile Tolerates Low O2 Tensions

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Nicolas Kint ◽  
Carolina Alves Feliciano ◽  
Maria C. Martins ◽  
Claire Morvan ◽  
Susana F. Fernandes ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Anaerobic Bacteria ◽  
Growth Defect ◽  
Strictly Anaerobic ◽  
Low Oxygen ◽  
Air Exposure ◽  
Vegetative Cells ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile is a major cause of diarrhea associated with antibiotherapy. After germination of C. difficile spores in the small intestine, vegetative cells are exposed to low oxygen (O2) tensions. While considered strictly anaerobic, C. difficile is able to grow in nonstrict anaerobic conditions (1 to 3% O2) and tolerates brief air exposure indicating that this bacterium harbors an arsenal of proteins involved in O2 detoxification and/or protection. Tolerance of C. difficile to low O2 tensions requires the presence of the alternative sigma factor, σB, involved in the general stress response. Among the genes positively controlled by σB, four encode proteins likely involved in O2 detoxification: two flavodiiron proteins (FdpA and FdpF) and two reverse rubrerythrins (revRbr1 and revRbr2). As previously observed for FdpF, we showed that both purified revRbr1 and revRbr2 harbor NADH-linked O2- and H2O2-reductase activities in vitro, while purified FdpA mainly acts as an O2-reductase. The growth of a fdpA mutant is affected at 0.4% O2, while inactivation of both revRbrs leads to a growth defect above 0.1% O2. O2-reductase activities of these different proteins are additive since the quadruple mutant displays a stronger phenotype when exposed to low O2 tensions compared to the triple mutants. Our results demonstrate a key role for revRbrs, FdpF, and FdpA proteins in the ability of C. difficile to grow in the presence of physiological O2 tensions such as those encountered in the colon. IMPORTANCE Although the gastrointestinal tract is regarded as mainly anoxic, low O2 tension is present in the gut and tends to increase following antibiotic-induced disruption of the host microbiota. Two decreasing O2 gradients are observed, a longitudinal one from the small to the large intestine and a second one from the intestinal epithelium toward the colon lumen. Thus, O2 concentration fluctuations within the gastrointestinal tract are a challenge for anaerobic bacteria such as C. difficile. This enteropathogen has developed efficient strategies to detoxify O2. In this work, we identified reverse rubrerythrins and flavodiiron proteins as key actors for O2 tolerance in C. difficile. These enzymes are responsible for the reduction of O2 protecting C. difficile vegetative cells from associated damages. Original and complex detoxification pathways involving O2-reductases are crucial in the ability of C. difficile to tolerate O2 and survive to O2 concentrations encountered in the gastrointestinal tract.

scholarly journals BrucellaPeriplasmic Protein EipB Is a Molecular Determinant of Cell Envelope Integrity and Virulence

2019 ◽  
Vol 201 (12) ◽  
Author(s):  
Julien Herrou ◽  
Jonathan W. Willett ◽  
Aretha Fiebig ◽  
Daniel M. Czyż ◽  
Jason X. Cheng ◽  
...  
Keyword(s):  
Cell Envelope ◽  
Mammalian Host ◽  
Periplasmic Protein ◽  
Periplasmic Space ◽  
Gene Encoding ◽  
Tetratricopeptide Repeats ◽  
Content Type ◽  
Family Protein ◽  
Synthetically Lethal

ABSTRACTThe Gram-negative cell envelope is a remarkable structure with core components that include an inner membrane, an outer membrane, and a peptidoglycan layer in the periplasmic space between. Multiple molecular systems function to maintain integrity of this essential barrier between the interior of the cell and its surrounding environment. We show that a conserved DUF1849 family protein, EipB, is secreted to the periplasmic space ofBrucellaspecies, a monophyletic group of intracellular pathogens. In the periplasm, EipB folds into an unusual 14-stranded β-spiral structure that resembles the LolA and LolB lipoprotein delivery system, though the overall fold of EipB is distinct from LolA/LolB. Deletion ofeipBresults in defects inBrucellacell envelope integrityin vitroand in maintenance of spleen colonization in a mouse model ofBrucella abortusinfection. Transposon disruption ofttpA, which encodes a periplasmic protein containing tetratricopeptide repeats, is synthetically lethal witheipBdeletion.ttpAis a reported virulence determinant inBrucella, and our studies ofttpAdeletion and overexpression strains provide evidence that this gene also contributes to cell envelope function. We conclude thateipBandttpAfunction in theBrucellaperiplasmic space to maintain cell envelope integrity, which facilitates survival in a mammalian host.IMPORTANCEBrucellaspecies cause brucellosis, a global zoonosis. A gene encoding a conserved DUF1849-family protein, which we have named EipB, is present in all sequencedBrucellaand several other genera in the classAlphaproteobacteria. The manuscript provides the first functional and structural characterization of a DUF1849 protein. We show that EipB is secreted to the periplasm where it forms a spiral-shaped antiparallel β protein that is a determinant of cell envelope integrityin vitroand virulence in an animal model of disease.eipBgenetically interacts withttpA, which also encodes a periplasmic protein. We propose that EipB and TtpA function as part of a system required for cell envelope homeostasis in selectAlphaproteobacteria.

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