scholarly journals Characterization of theVibrio choleraePhage Shock Protein Response

2019 ◽  
Vol 201 (14) ◽  
Author(s):  
Cara M. DeAngelis ◽  
Dhrubajyoti Nag ◽  
Jeffrey H. Withey ◽  
Jyl S. Matson
Keyword(s):  
Stress Response ◽  
Vibrio Cholerae ◽  
Membrane Damage ◽  
Regulatory Elements ◽  
Life Cycles ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
Genetic Components ◽  
Stress Response Pathway

ABSTRACTThe phage shock protein (Psp) system is a stress response pathway that senses and responds to inner membrane damage. The genetic components of the Psp system are present in several clinically relevant Gram-negative bacteria, includingVibrio cholerae. However, most of the current knowledge about the Psp response stems fromin vitrostudies inEscherichia coliandYersinia enterocolitica. In fact, the Psp response inV. choleraehas remained completely uncharacterized. In this study, we demonstrate thatV. choleraedoes have a functional Psp response system. We found that overexpression of GspD (EpsD), the type II secretion system secretin, induces the Psp response, whereas otherV. choleraesecretins do not. In addition, we have identified several environmental conditions that induce this stress response. Our studies on the genetic regulation and induction of the Psp system inV. choleraesuggest that the key regulatory elements are conserved with those of other Gram-negative bacteria. While apspnull strain is fully capable of colonizing the infant mouse intestine, it exhibits a colonization defect in a zebrafish model, indicating that this response may be important for disease transmission in the environment. Overall, these studies provide an initial understanding of a stress response pathway that has not been previously investigated inV. cholerae.IMPORTANCEVibrio choleraeleads a dual life cycle, as it can exist in the aquatic environment and colonize the human small intestine. In both life cycles,V. choleraeencounters a variety of stressful conditions, including fluctuating pH and temperature and exposure to other agents that may negatively affect cell envelope homeostasis. The phage shock protein (Psp) response is required to sense and respond to such insults in other bacteria but has remained unstudied inV. cholerae. Interestingly, the Psp system has protein homologs, principally, PspA, in a number of bacterial clades as well as in archaea and plants. Therefore, our findings not only fill a gap in knowledge about an unstudied extracytoplasmic stress response inV. cholerae, but also may have far-reaching implications.

scholarly journals A Stress Response Monitoring Lipoprotein Trafficking to the Outer Membrane

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Kerrie L. May ◽  
Kelly M. Lehman ◽  
Angela M. Mitchell ◽  
Marcin Grabowicz
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Outer Membrane ◽  
Stress Responses ◽  
Stress System ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
Essential Components ◽  
Trafficking Defects

ABSTRACTGram-negative bacteria produce lipid-anchored lipoproteins that are trafficked to their outer membrane (OM). These lipoproteins are essential components in each of the molecular machines that build the OM, including the Bam machine that assembles β-barrel proteins and the Lpt pathway that transports lipopolysaccharide. Stress responses are known to monitor Bam and Lpt function, yet no stress system has been found that oversees the fundamental process of lipoprotein trafficking. We used genetic and chemical biology approaches to induce several different lipoprotein trafficking stresses inEscherichia coli. Our results identified the Cpx two-component system as a stress response for monitoring trafficking. Cpx is activated by trafficking defects and is required to protect the cell against the consequence of the resulting stress. The OM-targeted lipoprotein NlpE acts as a sensor that allows Cpx to gauge trafficking efficiency. We reveal that NlpE signals to Cpx while it is transiting the inner membrane (IM)en routeto the OM and that only a small highly conserved N-terminal domain is required for signaling. We propose that defective trafficking causes NlpE to accumulate in the IM, activating Cpx to mount a transcriptional response that protects cells. Furthermore, we reconcile this new role of NlpE in signaling trafficking defects with its previously proposed role in sensing copper (Cu) stress by demonstrating that Cu impairs acylation of lipoproteins and, consequently, their trafficking to the OM.IMPORTANCEThe outer membrane built by Gram-negative bacteria such asEscherichia coliforms a barrier that prevents antibiotics from entering the cell, limiting clinical options at a time of prevalent antibiotic resistance. Stress responses ensure that barrier integrity is continuously maintained. We have identified the Cpx signal transduction system as a stress response that monitors the trafficking of lipid-anchored lipoproteins to the outer membrane. These lipoproteins are needed by every machine that builds the outer membrane. Cpx monitors just one lipoprotein, NlpE, to detect the efficiency of lipoprotein trafficking in the cell. NlpE and Cpx were previously shown to play a role in resistance to copper. We show that copper blocks lipoprotein trafficking, reconciling old and new observations. Copper is an important element in innate immunity against pathogens, and our findings suggest that NlpE and Cpx helpE. colisurvive the assault of copper on a key outer membrane assembly pathway.

scholarly journals Genomic and Resistance Epidemiology of Gram-Negative Bacteria in Africa: a Systematic Review and Phylogenomic Analyses from a One Health Perspective

mSystems ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
John Osei Sekyere ◽  
Melese Abate Reta
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Klebsiella Pneumoniae ◽  
Acinetobacter Baumannii ◽  
Vibrio Cholerae ◽  
Salmonella Enterica ◽  
Animal Health ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type

ABSTRACT Antibiotic resistance (AR) remains a major threat to public and animal health globally. However, AR ramifications in developing countries are worsened by limited molecular diagnostics, expensive therapeutics, inadequate numbers of skilled clinicians and scientists, and unsanitary environments. The epidemiology of Gram-negative bacteria, their AR genes, and geographical distribution in Africa are described here. Data were extracted and analyzed from English-language articles published between 2015 and December 2019. The genomes and AR genes of the various species, obtained from the Pathosystems Resource Integration Center (PATRIC) and NCBI were analyzed phylogenetically using Randomized Axelerated Maximum Likelihood (RAxML) and annotated with Figtree. The geographic location of resistant clones/clades was mapped manually. Thirty species from 31 countries and 24 genera from 41 countries were analyzed from 146 articles and 3,028 genomes, respectively. Genes mediating resistance to β-lactams (including blaTEM-1, blaCTX-M, blaNDM, blaIMP, blaVIM, and blaOXA-48/181), fluoroquinolones (oqxAB, qnrA/B/D/S, gyrA/B, and parCE mutations, etc.), aminoglycosides (including armA and rmtC/F), sulfonamides (sul1/2/3), trimethoprim (dfrA), tetracycline [tet(A/B/C/D/G/O/M/39)], colistin (mcr-1), phenicols (catA/B, cmlA), and fosfomycin (fosA) were mostly found in Enterobacter spp. and Klebsiella pneumoniae, and also in Serratia marcescens, Escherichia coli, Salmonella enterica, Pseudomonas, Acinetobacter baumannii, etc., on mostly IncF-type, IncX3/4, ColRNAI, and IncR plasmids, within IntI1 gene cassettes, insertion sequences, and transposons. Clonal and multiclonal outbreaks and dissemination of resistance genes across species and countries and between humans, animals, plants, and the environment were observed; Escherichia coli ST103, K. pneumoniae ST101, S. enterica ST1/2, and Vibrio cholerae ST69/515 were common strains. Most pathogens were of human origin, and zoonotic transmissions were relatively limited. IMPORTANCE Antibiotic resistance (AR) is one of the major public health threats and challenges to effective containment and treatment of infectious bacterial diseases worldwide. Here, we used different methods to map out the geographical hot spots, sources, and evolutionary epidemiology of AR. Escherichia coli, Klebsiella pneumoniae, Salmonella enterica, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., Neisseria meningitis/gonorrhoeae, Vibrio cholerae, Campylobacter jejuni, etc., were common pathogens shuttling AR genes in Africa. Transmission of the same clones/strains across countries and between animals, humans, plants, and the environment was observed. We recommend Enterobacter spp. or K. pneumoniae as better sentinel species for AR surveillance.

scholarly journals DNA Transport across the Outer and Inner Membranes of Naturally Transformable Vibrio cholerae Is Spatially but Not Temporally Coupled

mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Patrick Seitz ◽  
Melanie Blokesch
Keyword(s):  
Vibrio Cholerae ◽  
Physiological State ◽  
Gram Negative Bacteria ◽  
Dna Uptake ◽  
Dna Translocation ◽  
Natural Competence ◽  
Gram Negative ◽  
Content Type ◽  
Dna Transport ◽  
Uptake Process

ABSTRACTThe physiological state of natural competence for transformation allows certain bacteria to take up free DNA from the environment and to recombine such newly acquired DNA into their chromosomes. However, even though conserved components that are required to undergo natural transformation have been identified in several naturally competent bacteria, our knowledge of the underlying mechanisms of the DNA uptake process remains very limited. To better understand these mechanisms, we investigated the competence-mediated DNA transport in the naturally transformable pathogenVibrio cholerae. Previously, we used a cell biology-based approach to experimentally address an existing hypothesis, which suggested the competence protein ComEA plays a role in the DNA uptake process across the outer membrane of Gram-negative bacteria. Here, we extended this knowledge by investigating the dynamics of DNA translocation across both membranes. More precisely, we indirectly visualized the transfer of the external DNA from outside the cell into the periplasm followed by the shuttling of the DNA into the cytoplasm. Based on these data, we conclude that forV. cholerae, the DNA translocation across the outer and inner membranes is spatially but not temporally coupled.IMPORTANCEAs a mode of horizontal gene transfer, natural competence for transformation has contributed substantially to the plasticity of genomes and to bacterial evolution. Natural competence is often a tightly regulated process and is induced by diverse environmental cues. This is in contrast to the mechanistic aspects of the DNA translocation event, which are most likely conserved among naturally transformable bacteria. However, the DNA uptake process is still not well understood. We therefore investigated how external DNA reaches the cytosol of the naturally transformable bacteriumV. cholerae. More specifically, we provide evidence that the DNA translocation across the membranes is spatially but not temporally coupled. We hypothesize that this model also applies to other competent Gram-negative bacteria and that our study contributes to the general understanding of this important biological process.

scholarly journals Endopeptidase Regulation as a Novel Function of the Zur-Dependent Zinc Starvation Response

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Shannon G. Murphy ◽  
Laura Alvarez ◽  
Myfanwy C. Adams ◽  
Shuning Liu ◽  
Joshua S. Chappie ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Growth ◽  
Vibrio Cholerae ◽  
Zinc Homeostasis ◽  
Regulatory Control ◽  
Gram Negative Bacteria ◽  
Starvation Response ◽  
Gram Negative ◽  
Content Type ◽  
Antibiotic Development

ABSTRACTThe cell wall is a strong, yet flexible, meshwork of peptidoglycan (PG) that gives a bacterium structural integrity. To accommodate a growing cell, the wall is remodeled by both PG synthesis and degradation.Vibrio choleraeencodes a group of three nearly identical zinc-dependent endopeptidases (EPs) that are predicted to hydrolyze PG to facilitate cell growth. Two of these (ShyA and ShyC) are conditionally essential housekeeping EPs, while the third (ShyB) is not expressed under standard laboratory conditions. To investigate the role of ShyB, we conducted a transposon screen to identify mutations that activateshyBtranscription. We found thatshyBis induced as part of the Zur-mediated zinc starvation response, a mode of regulation not previously reported for cell wall lytic enzymes.In vivo, ShyB alone was sufficient to sustain cell growth in low-zinc environments.In vitro, ShyB retained itsd,d-endopeptidase activity against purified sacculi in the presence of the metal chelator EDTA at concentrations that inhibit ShyA and ShyC. This insensitivity to metal chelation is likely what enables ShyB to substitute for other EPs during zinc starvation. Our survey of transcriptomic data from diverse bacteria identified other candidate Zur-regulated EPs, suggesting that this adaptation to zinc starvation is employed by other Gram-negative bacteria.IMPORTANCEBacteria encode a variety of adaptations that enable them to survive during zinc starvation, a condition which is encountered both in natural environments and inside the human host. InVibrio cholerae, the causative agent of the diarrheal disease cholera, we have identified a novel member of this zinc starvation response, a cell wall hydrolase that retains function and is conditionally essential for cell growth in low-zinc environments. Other Gram-negative bacteria contain homologs that appear to be under similar regulatory control. These findings are significant because they represent, to our knowledge, the first evidence that zinc homeostasis influences cell wall turnover. Anti-infective therapies commonly target the bacterial cell wall; therefore, an improved understanding of how the cell wall adapts to host-induced zinc starvation could lead to new antibiotic development. Such therapeutic interventions are required to combat the rising threat of drug-resistant infections.

scholarly journals Secretome Analysis of Vibrio cholerae Type VI Secretion System Reveals a New Effector-Immunity Pair

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Emrah Altindis ◽  
Tao Dong ◽  
Christy Catalano ◽  
John Mekalanos
Keyword(s):  
Vibrio Cholerae ◽  
Bioinformatics Analysis ◽  
Secretion System ◽  
Comparative Proteomics ◽  
Gram Negative Bacteria ◽  
Type Vi Secretion System ◽  
Immunity Protein ◽  
Gram Negative ◽  
Content Type ◽  
Type Vi Secretion

ABSTRACT The type VI secretion system (T6SS) is a dynamic macromolecular organelle that many Gram-negative bacteria use to inhibit or kill other prokaryotic or eukaryotic cells. The toxic effectors of T6SS are delivered to the prey cells in a contact-dependent manner. In Vibrio cholerae, the etiologic agent of cholera, T6SS is active during intestinal infection. Here, we describe the use of comparative proteomics coupled with bioinformatics to identify a new T6SS effector-immunity pair. This analysis was able to identify all previously identified secreted substrates of T6SS except PAAR (proline, alanine, alanine, arginine) motif-containing proteins. Additionally, this approach led to the identification of a new secreted protein encoded by VCA0285 (TseH) that carries a predicted hydrolase domain. We confirmed that TseH is toxic when expressed in the periplasm of Escherichia coli and V. cholerae cells. The toxicity observed in V. cholerae was suppressed by coexpression of the protein encoded by VCA0286 (TsiH), indicating that this protein is the cognate immunity protein of TseH. Furthermore, exogenous addition of purified recombinant TseH to permeabilized E. coli cells caused cell lysis. Bioinformatics analysis of the TseH protein sequence suggest that it is a member of a new family of cell wall-degrading enzymes that include proteins belonging to the YD repeat and Rhs superfamilies and that orthologs of TseH are likely expressed by species belonging to phyla as diverse as Bacteroidetes and Proteobacteria. IMPORTANCE The Gram-negative bacterium Vibrio cholerae causes cholera, a severe and often lethal diarrheal disease. The 2010-2012 epidemic in Haiti and new explosive epidemics in Africa show that cholera remains a significant global public health problem. The type VI secretion system (T6SS) is a dynamic organelle expressed by many Gram-negative bacteria, which use it to inject toxic effector proteins into eukaryotic and bacterial prey cells. In this study, we applied a comparative proteomics approach to the V. cholerae T6SS secretome to identify new substrates of this secretion apparatus. We show that the product of the gene VCA0285 is likely a new peptidoglycan hydrolase that is secreted by T6SS and that its cognate immunity protein is encoded by the gene that is immediately downstream (VCA0286). Bioinformatics analysis shows that VCA0285 carries four conserved motifs that likely define a large family of hydrolases with antibacterial activity. The identification of new antibacterial T6SS effectors provides useful information for the development of novel antibiotics and therapeutic agents.

scholarly journals Recognition of β-Strand Motifs by RseB Is Required for σEActivity in Escherichia coli

2011 ◽  
Vol 193 (22) ◽  
pp. 6179-6186 ◽  
Author(s):  
Adam Kulp ◽  
Meta J. Kuehn
Keyword(s):  
Stress Response ◽  
Stress Responses ◽  
Outer Membrane Proteins ◽  
Harsh Environments ◽  
Gram Negative Bacteria ◽  
Dependent Manner ◽  
Gram Negative ◽  
Stress Response Pathway ◽  
Envelope Stress ◽  
Different Types

Gram-negative bacteria react to misfolded proteins in the envelope through a myriad of different stress response pathways. This cohort of pathways allows the bacteria to specifically respond to different types of damage, and many of these have been discovered to have key roles in the virulence of bacterial pathogens. Misfolded outer membrane proteins (OMPs) are typically recognized by the σEpathway, a highly conserved envelope stress response pathway. We examined the features of misfolded OMPs with respect to their ability to generate envelope stress responses. We determined that the secondary structure, particularly the potential to form β strands, is critical to inducing the σEresponse in an RseB-dependent manner. The sequence of the potential β-strand motif modulates the strength of the σEresponse generated by the constructs. By understanding the details of how such stress response pathways are activated, we can gain a greater understanding of how bacteria survive in harsh environments.

scholarly journals Improved Antimicrobial Activities of Synthetic-Hybrid Bacteriocins Designed from Enterocin E50-52 and Pediocin PA-1

2014 ◽  
Vol 81 (5) ◽  
pp. 1661-1667 ◽  
Author(s):  
Santosh Kumar Tiwari ◽  
Katia Sutyak Noll ◽  
Veronica L. Cavera ◽  
Michael L. Chikindas
Keyword(s):  
Micrococcus Luteus ◽  
Electrical Potential ◽  
Gram Negative Bacteria ◽  
Additional Advantage ◽  
Gram Negative ◽  
Content Type ◽  
Intracellular Atp ◽  
Hybrid Peptides ◽  
C Terminus ◽  
N Terminus

ABSTRACTTwo hybrid bacteriocins, enterocin E50-52/pediocin PA-1 (EP) and pediocin PA-1/enterocin E50-52 (PE), were designed by combining the N terminus of enterocin E50-52 and the C terminus of pediocin PA-1 and by combining the C terminus of pediocin PA-1 and the N terminus of enterocin E50-52, respectively. Both hybrid bacteriocins showed reduced MICs compared to those of their natural counterparts. The MICs of hybrid PE and EP were 64- and 32-fold lower, respectively, than the MIC of pediocin PA-1 and 8- and 4-fold lower, respectively, than the MIC of enterocin E50-52. In this study, the effect of hybrid as well as wild-type (WT) bacteriocins on the transmembrane electrical potential (ΔΨ) and their ability to induce the efflux of intracellular ATP were investigated. Enterocin E50-52, pediocin PA-1, and hybrid bacteriocin PE were able to dissipate ΔΨ, but EP was unable to deplete this component. Both hybrid bacteriocins caused a loss of the intracellular concentration of ATP. EP, however, caused a faster efflux than PE and enterocin E50-52. Enterocin E50-52 and hybrids PE and EP were active against the Gram-positive and Gram-negative bacteria tested, such asMicrococcus luteus,Salmonella entericaserovar Enteritidis 20E1090, andEscherichia coliO157:H7. The hybrid bacteriocins designed and described herein are antimicrobial peptides with MICs lower those of their natural counterparts. Both hybrid peptides induce the loss of intracellular ATP and are capable of inhibiting Gram-negative bacteria, and PE dissipates the electrical potential. In this study, the MIC of hybrid bacteriocin PE decreased 64-fold compared to the MIC of its natural peptide counterpart, pediocin PA-1. Inhibition of Gram-negative pathogens confers an additional advantage for the application of these peptides in therapeutics.

scholarly journals A High-Throughput Approach To Identify Compounds That Impair Envelope Integrity in Escherichia coli

2016 ◽  
Vol 60 (10) ◽  
pp. 5995-6002 ◽  
Author(s):  
Kristin R. Baker ◽  
Bimal Jana ◽  
Henrik Franzyk ◽  
Luca Guardabassi
Keyword(s):  
Escherichia Coli ◽  
High Throughput ◽  
High Throughput Screening ◽  
Gram Negative Bacteria ◽  
Chromogenic Substrate ◽  
Intrinsic Resistance ◽  
Gram Negative ◽  
Content Type ◽  
E Coli ◽  
Screening Platform

ABSTRACTThe envelope of Gram-negative bacteria constitutes an impenetrable barrier to numerous classes of antimicrobials. This intrinsic resistance, coupled with acquired multidrug resistance, has drastically limited the treatment options against Gram-negative pathogens. The aim of the present study was to develop and validate an assay for identifying compounds that increase envelope permeability, thereby conferring antimicrobial susceptibility by weakening of the cell envelope barrier in Gram-negative bacteria. A high-throughput whole-cell screening platform was developed to measureEscherichia colienvelope permeability to a β-galactosidase chromogenic substrate. The signal produced by cytoplasmic β-galactosidase-dependent cleavage of the chromogenic substrate was used to determine the degree of envelope permeabilization. The assay was optimized by using known envelope-permeabilizing compounds andE. coligene deletion mutants with impaired envelope integrity. As a proof of concept, a compound library comprising 36 peptides and 45 peptidomimetics was screened, leading to identification of two peptides that substantially increased envelope permeability. Compound 79 reduced significantly (from 8- to 125-fold) the MICs of erythromycin, fusidic acid, novobiocin and rifampin and displayed synergy (fractional inhibitory concentration index, <0.2) with these antibiotics by checkerboard assays in two genetically distinctE. colistrains, including the high-risk multidrug-resistant, CTX-M-15-producing sequence type 131 clone. Notably, in the presence of 0.25 μM of this peptide, both strains were susceptible to rifampin according to the resistance breakpoints (R> 0.5 μg/ml) for Gram-positive bacterial pathogens. The high-throughput screening platform developed in this study can be applied to accelerate the discovery of antimicrobial helper drug candidates and targets that enhance the delivery of existing antibiotics by impairing envelope integrity in Gram-negative bacteria.

Microbiological pattern of prosthetic hip and knee infections: a high-volume, single-centre experience in China

2021 ◽  
Author(s):  
Yali Yu ◽  
Yiyi Kong ◽  
Jing Ye ◽  
Aiguo Wang ◽  
Wenteng Si
Keyword(s):  
Antibiotic Treatment ◽  
Prolonged Treatment ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Musculoskeletal Infection ◽  
Gram Negative ◽  
Content Type ◽  
Empirical Antibiotic Treatment ◽  
Link Type

Introduction. Prosthetic joint infection (PJI) is a serious complication after arthroplasty, which results in high morbidity, prolonged treatment and considerable healthcare expenses in the absence of accurate diagnosis. In China, microbiological data on PJIs are still scarce. Hypothesis/Gap Statement. The incidence of PJI is increasing year by year, and the proportion of drug-resistant bacteria infection is nicreasing, which brings severe challenges to the treatment of infection. Aim. This study aimed to identify the pathogens in PJIs, multi-drug resistance, and evaluate the effect of the treatment regimen in patients with PJI. Methodology. A total of 366 consecutive cases of PJI in the hip or knee joint were admitted at the Orthopedic Surgery Center in Zhengzhou, China from January 2012 to December 2018. Infections were confirmed in accordance with the Infectious Diseases Society of America and the Musculoskeletal Infection Society (MSIS) criteria. Concurrently, patient demographic data, incidence and antibiotic resistance were investigated. Statistical differences were analysed using Fisher’s exact test or chi-square test. Results. Altogether, 318 PJI cases satisfying the inclusion criteria were enrolled in this study, including 148 with hip PJIs and 170 with knee PJIs. The average age of patients with hip PJIs was lesser than that of patients with knee PJIs (56.4 vs. 68.6 years). Meanwhile, coagulase-negative staphylococcus (CNS, n=81, 25.5 %) was the predominant causative pathogen, followed by Staphylococcus aureus (n=67, 21.1 %). Methicillin-resistant Staphylococcus (MRS) was identified in 28.9 % of PJI patients. In addition, fungus accounted for 4.8 % (n=15), non-tuberculosis mycobacterium accounted for 1.6 % (n=5), polymicrobial pathogens accounted for 21.7 % (n=69), and Gram-negative bacteria accounted for 7.9 % (n=25) of the total infections. The results of antibiotic susceptibility testing showed that gentamicin and clindamycin β-lactam antibiotics were poorly susceptible to Gram-positive isolates, but they were sensitive to rifampicin, linezolid and vancomycin. While antibiotics such as amikacin and imipenem were effective against Gram-negative bacteria, there was a high resistance rate of other pathogens to gentamicin, clindamycin and some quinolone antibacterial drugs. Empirical antibiotic treatment should combine vancomycin and cephalosporin, levofloxacin or clindamycin. When the pathogen is confirmed, the treatment should be individualized. Conclusions. The prevalence of culture-negative PJIs is still very high. Gram-positive bacteria are still the main type of pathogens that cause PJIs. Attention should be paid to the high incidence of MRS, such as MRSA and MR-CNS, among PJI patients. Empirical antibiotic treatment should cover Gram-positive isolates, especially Staphylococcus .

scholarly journals YejM Modulates Activity of the YciM/FtsH Protease Complex To Prevent Lethal Accumulation of Lipopolysaccharide

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Randi L. Guest ◽  
Daniel Samé Guerra ◽  
Maria Wissler ◽  
Jacqueline Grimm ◽  
Thomas J. Silhavy
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Gram Negative Bacteria ◽  
Inner Membrane ◽  
Gram Negative ◽  
Content Type ◽  
Essential Protein ◽  
Ftsh Protease ◽  
Acyl Chains ◽  
Lipid Balance

ABSTRACT Lipopolysaccharide (LPS) is an essential glycolipid present in the outer membrane (OM) of many Gram-negative bacteria. Balanced biosynthesis of LPS is critical for cell viability; too little LPS weakens the OM, while too much LPS is lethal. In Escherichia coli, this balance is maintained by the YciM/FtsH protease complex, which adjusts LPS levels by degrading the LPS biosynthesis enzyme LpxC. Here, we provide evidence that activity of the YciM/FtsH protease complex is inhibited by the essential protein YejM. Using strains in which LpxC activity is reduced, we show that yciM is epistatic to yejM, demonstrating that YejM acts upstream of YciM to prevent toxic overproduction of LPS. Previous studies have shown that this toxicity can be suppressed by deleting lpp, which codes for a highly abundant OM lipoprotein. It was assumed that deletion of lpp restores lipid balance by increasing the number of acyl chains available for glycerophospholipid biosynthesis. We show that this is not the case. Rather, our data suggest that preventing attachment of lpp to the peptidoglycan sacculus allows excess LPS to be shed in vesicles. We propose that this loss of OM material allows continued transport of LPS to the OM, thus preventing lethal accumulation of LPS within the inner membrane. Overall, our data justify the commitment of three essential inner membrane proteins to avoid toxic over- or underproduction of LPS. IMPORTANCE Gram-negative bacteria are encapsulated by an outer membrane (OM) that is impermeable to large and hydrophobic molecules. As such, these bacteria are intrinsically resistant to several clinically relevant antibiotics. To better understand how the OM is established or maintained, we sought to clarify the function of the essential protein YejM in Escherichia coli. Here, we show that YejM inhibits activity of the YciM/FtsH protease complex, which regulates synthesis of the essential OM glycolipid lipopolysaccharide (LPS). Our data suggest that disrupting proper communication between LPS synthesis and transport to the OM leads to accumulation of LPS within the inner membrane (IM). The lethality associated with this event can be suppressed by increasing OM vesiculation. Our research has identified a completely novel signaling pathway that we propose coordinates LPS synthesis and transport.

Sign in / Sign up

Export Citation Format

Share Document