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stress response membrane envelope bacteria

Julia F Nepper, Yin C Lin, Douglas B Weibel
Biofilm formation is a complex process that requires a number of transcriptional, proteomic, and physiological changes to enable bacterial survival. The lipid membrane presents a barrier to communication between the machinery within bacteria and the physical and chemical features of their extracellular environment, and yet little is known about how the membrane influences biofilm development. We found that depleting the anionic phospholipid cardiolipin reduces biofilm formation in Escherichia coli cells by as much as 50%...
February 19, 2019: Journal of Bacteriology
Xiaozhen Huang, Xiujuan Zhou, Ben Jia, Nuo Li, Jingya Jia, Mu He, Yichen He, Xiaojie Qin, Yan Cui, Chunlei Shi, Yanhong Liu, Xianming Shi
The survival mechanism of Salmonella enterica serovar Enteritidis in antibacterial egg white is not fully understood. In our lab, an egg white-resistant strain, S. Enteritidis SJTUF 10978, was identified. Cell envelope damage and osmotic stress response (separation of cell wall and inner membrane as well as cytoplasmic shrinkage) of this strain surviving in egg white were identified through microscopic observation. RNA-Seq analysis of the transcriptome of Salmonella survival in egg white showed that a considerable number of genes involved in DNA damage repair, alkaline pH adaptation, osmotic stress adaptation, envelope damage repair, Salmonella pathogenicity island 2 (SPI-2), iron absorption, and biotin synthesis were significantly upregulated (fold change ≥ 2) in egg white, indicating that these pathways or genes might be critical for bacterial survival...
February 13, 2019: MSphere
Niccolò Morè, Alessandra M Martorana, Jacob Biboy, Christian Otten, Matthias Winkle, Carlos K Gurnani Serrano, Alejandro Montón Silva, Lisa Atkinson, Hamish Yau, Eefjan Breukink, Tanneke den Blaauwen, Waldemar Vollmer, Alessandra Polissi
Gram-negative bacteria have a tripartite cell envelope with the cytoplasmic membrane (CM), a stress-bearing peptidoglycan (PG) layer, and the asymmetric outer membrane (OM) containing lipopolysaccharide (LPS) in the outer leaflet. Cells must tightly coordinate the growth of their complex envelope to maintain cellular integrity and OM permeability barrier function. The biogenesis of PG and LPS relies on specialized macromolecular complexes that span the entire envelope. In this work, we show that Escherichia coli cells are capable of avoiding lysis when the transport of LPS to the OM is compromised, by utilizing LD-transpeptidases (LDTs) to generate 3-3 cross-links in the PG...
February 5, 2019: MBio
Gracjana Klein, Satish Raina
Distinguishing feature of the outer membrane (OM) of Gram-negative bacteria is its asymmetry due to the presence of lipopolysaccharide (LPS) in the outer leaflet of the OM and phospholipids in the inner leaflet. Recent studies have revealed the existence of regulatory controls that ensure a balanced biosynthesis of LPS and phospholipids, both of which are essential for bacterial viability. LPS provides the essential permeability barrier function and act as a major virulence determinant. In Escherichia coli , more than 100 genes are required for LPS synthesis, its assembly at inner leaflet of the inner membrane (IM), extraction from the IM, translocation to the OM, and in its structural alterations in response to various environmental and stress signals...
January 16, 2019: International Journal of Molecular Sciences
Goizeder Almagro, Alejandro M Viale, Manuel Montero, Francisco José Muñoz, Edurne Baroja-Fernández, Hirotada Mori, Javier Pozueta-Romero
ADP-glucose is the precursor of glycogen biosynthesis in bacteria, and a compound abundant in the starchy plant organs ingested by many mammals. Here we show that the enteric species Escherichia coli is capable of scavenging exogenous ADP-glucose for use as a glycosyl donor in glycogen biosynthesis and feed the adenine nucleotide pool. To unravel the molecular mechanisms involved in this process, we screened the E. coli single-gene deletion mutants of the Keio collection for glycogen content in ADP-glucose-containing culture medium...
October 19, 2018: Scientific Reports
Michael Y Galperin
Bacterial signal transduction systems are responsible for sensing environmental cues and adjusting the cellular behaviour and/or metabolism in response to these cues. They also monitor the intracellular conditions and the status of the cell envelope and the cytoplasmic membrane and trigger various stress responses to counteract adverse changes. This surveillance involves several classes of sensor proteins: histidine kinases; chemoreceptors; membrane components of the sugar phosphotransferase system; adenylate, diadenylate and diguanylate cyclases and certain cAMP, c-di-AMP and c-di-GMP phosphodiesterases; extracytoplasmic function sigma factors and Ser/Thr/Tyr protein kinases and phosphoprotein phosphatases...
September 5, 2018: Environmental Microbiology
Magdalena Szczesny, Christophe Beloin, Jean-Marc Ghigo
Biofilms are often described as protective shelters that preserve bacteria from hostile surroundings. However, biofilm bacteria are also exposed to various stresses and need to adjust to the heterogeneous physicochemical conditions prevailing within biofilms. In Gram-negative bacteria, such adaptations can result in modifications of the lipopolysaccharide, a major component of the outer membrane characterized by a highly dynamic structure responding to environmental changes. We previously showed that Gram-negative biofilm bacteria undergo an increase in lipid A palmitoylation mediated by the PagP enzyme, contributing to increased resistance to host defenses...
August 21, 2018: MBio
Sandrine Auger, Céline Henry, Christine Péchoux, Sneha Suman, Nathalie Lejal, Nicolas Bertho, Thibaut Larcher, Slavica Stankic, Jasmina Vidic
The increasing number of multidrug resistant bacteria raises a serious public-health concern, which is exacerbated by the lack of new antibiotics. Metal oxide nanoparticles are already applied as an antibacterial additive in various products used in everyday life but their modes of action have remained unclear. Moreover, their potential negative effects to human health are still under evaluation. We explored effects of mixed metal oxide Zn0.15 Mg0.85 O on Bacillus subtilis, as a model bacterial organism, and on murine macrophages...
August 16, 2018: Scientific Reports
Angela M Mitchell, Tharan Srikumar, Thomas J Silhavy
Gram-negative bacteria have an outer membrane (OM) impermeable to many toxic compounds that can be further strengthened during stress. In Enterobacteriaceae , the envelope contains enterobacterial common antigen (ECA), a carbohydrate-derived moiety conserved throughout Enterobacteriaceae , the function of which is poorly understood. Previously, we identified several genes in Escherichia coli K-12 responsible for an RpoS-dependent decrease in envelope permeability during carbon-limited stationary phase. For one of these, yhdP , a gene of unknown function, deletion causes high levels of both vancomycin and detergent sensitivity, independent of growth phase...
August 7, 2018: MBio
Anna I Weaver, Shannon G Murphy, Benjamin D Umans, Srikar Tallavajhala, Ikenna Onyekwere, Stephen Wittels, Jung-Ho Shin, Michael VanNieuwenhze, Matthew K Waldor, Tobias Dörr
Many bacteria are resistant to killing (tolerant) by typically bactericidal antibiotics due to their ability to counteract drug-induced cell damage. Vibrio cholerae , the cholera agent, displays an unusually high tolerance to diverse inhibitors of cell wall synthesis. Exposure to these agents, which in other bacteria leads to lysis and death, results in a breakdown of the cell wall and subsequent sphere formation in V. cholerae Spheres readily recover to rod-shaped cells upon antibiotic removal, but the mechanisms mediating the recovery process are not well characterized...
October 2018: Antimicrobial Agents and Chemotherapy
Kathrin S Fröhlich, Susan Gottesman
The ability of bacteria to thrive in diverse habitats and to adapt to ever-changing environmental conditions relies on the rapid and stringent modulation of gene expression. It has become evident in the past decade that small regulatory RNAs (sRNAs) are central components of networks controlling the bacterial responses to stress. Functioning at the posttranscriptional level, sRNAs base-pair with cognate mRNAs to alter translation, stability, or both to either repress or activate the targeted transcripts; the RNA chaperone Hfq participates in stabilizing sRNAs and in promoting pairing between target and sRNA...
July 2018: Microbiology Spectrum
Inês N Silva, Filipa D Pessoa, Marcelo J Ramires, Mário R Santos, Jörg D Becker, Vaughn S Cooper, Leonilde M Moreira
Bacteria from the Burkholderia cepacia complex grow in different natural and man-made environments and are feared opportunistic pathogens that cause chronic respiratory infections in cystic fibrosis patients. Previous studies showed that Burkholderia mucoid clinical isolates grown under stress conditions give rise to nonmucoid variants devoid of the exopolysaccharide cepacian. Here, we determined that a major cause of the nonmucoid morphotype involves nonsynonymous mutations and small indels in the ompR gene encoding a response regulator of a two-component regulatory system...
September 1, 2018: Journal of Bacteriology
Soraya Omardien, Jan W Drijfhout, Henk van Veen, Soraya Schachtschabel, Martijn Riool, Leendert W Hamoen, Stanley Brul, Sebastian A J Zaat
BACKGROUND: Three amphipathic cationic antimicrobial peptides (AMPs) were characterized by determining their effect on Gram-positive bacteria using Bacillus subtilis strain 168 as a model organism. These peptides were TC19 and TC84, derivatives of thrombocidin-1 (TC-1), the major AMPs of human blood platelets, and Bactericidal Peptide 2 (BP2), a synthetic designer peptide based on human bactericidal permeability increasing protein (BPI). METHODS: To elucidate the possible mode of action of the AMPs we performed a transcriptomic analysis using microarrays...
November 2018: Biochimica et biophysica acta. Biomembranes
Imke Spöring, Sebastian Felgner, Matthias Preuße, Denitsa Eckweiler, Manfred Rohde, Susanne Häussler, Siegfried Weiss, Marc Erhardt
Flagellum-driven motility of Salmonella enterica serovar Typhimurium facilitates host colonization. However, the large extracellular flagellum is also a prime target for the immune system. As consequence, expression of flagella is bistable within a population of Salmonella , resulting in flagellated and nonflagellated subpopulations. This allows the bacteria to maximize fitness in hostile environments. The degenerate EAL domain protein RflP (formerly YdiV) is responsible for the bistable expression of flagella by directing the flagellar master regulatory complex FlhD4 C2 with respect to proteolytic degradation...
May 1, 2018: MBio
Janani Ravi, Vivek Anantharaman, L Aravind, Maria Laura Gennaro
The phage shock protein (Psp) stress-response system protects bacteria from envelope stress through a cascade of interactions with other proteins and membrane lipids to stabilize the cell membrane. A key component of this multi-gene system is PspA, an effector protein that is found in diverse bacterial phyla, archaea, cyanobacteria, and chloroplasts. Other members of the Psp system include the cognate partners of PspA that are part of known operons: pspF||pspABC in Proteobacteria, liaIHGFSR in Firmicutes, and clgRpspAMN in Actinobacteria...
May 2018: Antonie Van Leeuwenhoek
Sushovan Dam, Jean-Marie Pagès, Muriel Masi
Bacteria have evolved several strategies to survive a myriad of harmful conditions in the environment and in hosts. In Gram-negative bacteria, responses to nutrient limitation, oxidative or nitrosative stress, envelope stress, exposure to antimicrobials and other growth-limiting stresses have been linked to the development of antimicrobial resistance. This results from the activation of protective changes to cell physiology (decreased outer membrane permeability), resistance transporters (drug efflux pumps), resistant lifestyles (biofilms, persistence) and/or resistance mutations (target mutations, production of antibiotic modification/degradation enzymes)...
March 2018: Microbiology
Christian Eberlein, Thomas Baumgarten, Stephan Starke, Hermann J Heipieper
Bacteria have evolved an array of adaptive mechanisms enabling them to survive and grow in the presence of different environmental stresses. These mechanisms include either modifications of the membrane or changes in the overall energy status, cell morphology, and cell surface properties. Long-term adaptations are dependent on transcriptional regulation, the induction of anabolic pathways, and cell growth. However, to survive sudden environmental changes, bacterial short-term responses are essential to keep the cells alive after the occurrence of an environmental stress factor such as heat shock or the presence of toxic organic solvents...
March 2018: Applied Microbiology and Biotechnology
Aida Ebrahimi, Laszlo N Csonka, Muhammad A Alam
Heat treatment is one of the most widely used methods for inactivation of bacteria in food products. Heat-induced loss of bacterial viability has been variously attributed to protein denaturation, oxidative stress, or membrane leakage; indeed, it is likely to involve a combination of these processes. We examine the effect of mild heat stress (50-55°C for ≤12 min) on cell permeability by directly measuring the electrical conductance of samples of Salmonella enterica serovar Typhimurium to answer a fundamental biophysical question, namely, how bacteria die under mild heat stress...
February 6, 2018: Biophysical Journal
Sushovan Dam, Jean-Marie Pagès, Muriel Masi
Antibiotic resistant Gram-negative bacteria are a serious threat for public health. The permeation of antibiotics through their outer membrane is largely dependent on porin, changes in which cause reduced drug uptake and efficacy. Escherichia coli produces two major porins, OmpF and OmpC. MicF and MicC are small non-coding RNAs (sRNAs) that modulate the expression of OmpF and OmpC, respectively. In this work, we investigated factors that lead to increased production of MicC. micC promoter region was fused to lacZ , and the reporter plasmid was transformed into E...
December 6, 2017: Antibiotics
Verónica Urdaneta, Josep Casadesús
Bile salts and bacteria have intricate relationships. The composition of the intestinal pool of bile salts is shaped by bacterial metabolism. In turn, bile salts play a role in intestinal homeostasis by controlling the size and the composition of the intestinal microbiota. As a consequence, alteration of the microbiome-bile salt homeostasis can play a role in hepatic and gastrointestinal pathological conditions. Intestinal bacteria use bile salts as environmental signals and in certain cases as nutrients and electron acceptors...
2017: Frontiers in Medicine
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