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stress response membrane bacteria

Yu Hang Leung, Xiaoying Xu, Angel P Y Ma, Fangzhou Liu, Alan M C Ng, Zhiyong Shen, Lee A Gethings, Mu Yao Guo, Aleksandra B Djurišić, Patrick K H Lee, Hung Kay Lee, Wai Kin Chan, Frederick C C Leung
We performed a comprehensive investigation of the toxicity of ZnO and TiO2 nanoparticles using Escherichia coli as a model organism. Both materials are wide band gap n-type semiconductors and they can interact with lipopolysaccharide molecules present in the outer membrane of E. coli, as well as produce reactive oxygen species (ROS) under UV illumination. Despite the similarities in their properties, the response of the bacteria to the two nanomaterials was fundamentally different. When the ROS generation is observed, the toxicity of nanomaterial is commonly attributed to oxidative stress and cell membrane damage caused by lipid peroxidation...
October 12, 2016: Scientific Reports
J Szewczyk, J-F Collet
Bacterial lipoproteins are a very diverse group of proteins characterized by the presence of an N-terminal lipid moiety that serves as a membrane anchor. Lipoproteins have a wide variety of crucial functions, ranging from envelope biogenesis to stress response. In Gram-negative bacteria, lipoproteins can be targeted to various destinations in the cell, including the periplasmic side of the cytoplasmic or outer membrane, the cell surface or the external milieu. The sorting mechanisms have been studied in detail in Escherichia coli, but exceptions to the rules established in this model bacterium exist in other bacteria...
2016: Advances in Microbial Physiology
Josué Flores-Kim, Andrew J Darwin
: The Phage shock protein (Psp) system is a widely conserved cell envelope stress response that is essential for the virulence of some bacteria, including Yersinia enterocolitica Recruitment of PspA by the inner membrane PspB•PspC complex characterizes the activated state of this response. The PspB•PspC complex has been proposed to be a stress-responsive switch, changing from an OFF to an ON state in response to an inducing stimulus. In the OFF state, PspA cannot access its binding site in the C-terminal cytoplasmic domain of PspC (PspC(CT)) because this site is bound to PspB...
October 3, 2016: Journal of Bacteriology
Brittany Barreto, Elizabeth Rogers, Jun Xia, Ryan L Frisch, Megan Richters, Devon M Fitzgerald, Susan M Rosenberg
: Microbes and human cells possess mechanisms of mutagenesis activated by stress responses. Stress-inducible mutagenesis mechanisms may provide important models for mutagenesis that drives host-pathogen interactions, antibiotic resistance, and possibly much of evolution generally. In Escherichia coli, repair of DNA double-strand breaks is switched to a mutagenic mode, using error-prone DNA polymerases, via the SOS DNA-damage and the general (σ(S)) stress responses. We investigated small RNA (sRNA) clients of Hfq, an RNA chaperone that promotes mutagenic break repair (MBR), and found that GcvB promotes MBR by allowing a robust σ(S) response, achieved via opposing the membrane stress (σ(E)) response...
October 3, 2016: Journal of Bacteriology
Borui Pi, Dongliang Yu, Xiaoting Hua, Zhi Ruan, Yunsong Yu
During the last decade, an increasing amount of attention has focused on the potential threat of triclosan to both the human body and environmental ecology. However, the role of triclosan in the development of drug resistance and cross resistance is still in dispute ascribed to largely unknown of triclosan resistance mechanism. In this work, Acinetobacter baumannii MDR-ZJ06, a multidrug-resistant strain, was induced by triclosan, and the genomic variation and transcriptional levels were investigated, respectively...
September 24, 2016: Archives of Microbiology
Magdalena A Olszewska, Aleksandra M Kocot, Anna Nynca, Łucja Łaniewska-Trokenheim
pH stress is recognized as an important feature for Lactobacillus in relation to lifestyle and commercial utility. Hence, this study aims to investigate the cell function of Lactobacilli cells subjected to pHs between 7.0 and 2.0. For this purpose, the Lactobacilli isolates of vegetable origin were first hybridized with fluorescent oligonucleotide rRNA probes for detecting Lactobacillus species. Then, cells were exposed to pH stress and labelled with fluorescent probes, carboxyfluorescein diacetate (CFDA) and propidium iodine (PI), which provided the insight into esterase activity and membrane integrity of cells...
November 2016: Microbiological Research
Christian Lorenz, Thomas J Dougherty, Stephen Lory
: In Gram-negative bacteria a dedicated machinery, consisting of LolABCDE components targets lipoproteins to the outer membrane. We used a previously identified small molecule inhibitor of the LolCDE complex of Escherichia coli to assess the global transcriptional consequences of interference with lipoprotein transport. Exposure of E. coli to the LolCDE inhibitor at concentrations leading to minimal and significant growth inhibition, followed by RNA-seq, identified a small group of genes, whose transcripts were decreased and a larger group where mRNA levels increased 10-100 fold when compared to untreated cells...
September 19, 2016: Journal of Bacteriology
Esther Braselmann, Julie L Chaney, Matthew M Champion, Patricia L Clark
The periplasm of Gram-negative bacteria includes a variety of molecular chaperones that shepherd the folding and targeting of secreted proteins. A central player of this quality control network is DegP, a protease also suggested to have a chaperone function. We serendipitously discovered that production of the Bordetella pertussis autotransporter virulence protein pertactin is lethal in Escherichia coli ΔdegP strains. We investigated specific contributions of DegP to secretion of pertactin as a model system to test the functions of DegP in vivo...
2016: PloS One
Lilian P Prione, Luiz R Olchanheski, Leandro D Tullio, Bruno C E Santo, Péricles M Reche, Paula F Martins, Giselle Carvalho, Ivo M Demiate, Sônia A V Pileggi, Manuella N Dourado, Rosilene A Prestes, Michael J Sadowsky, Ricardo A Azevedo, Marcos Pileggi
Callisto(®), containing the active ingredient mesotrione (2-[4-methylsulfonyl-2-nitrobenzoyl]1,3-cyclohenanedione), is a selective herbicide that controls weeds in corn crops and is a potential environmental contaminant. The objective of this work was to evaluate enzymatic and structural changes in Pantoea ananatis, a strain isolated from water, in response to exposure to this herbicide. Despite degradation of mesotrione, probably due a glutathione-S-transferase (GST) pathway in Pantoea ananatis, this herbicide induced oxidative stress by increasing hydrogen peroxide production...
December 2016: AMB Express
Carla C C R de Carvalho, Martin A Fischer, Sandra Kirsten, Birgit Würz, Lukas Y Wick, Hermann J Heipieper
Mycolata form a group of Gram-positive bacteria with unique cell envelope structures that are known for their high tolerance against antibiotics and both aromatic and aliphatic hydrocarbons. An important part of the unique surface structure of the mycolata is the presence of long chain α-alkyl-β-hydroxy fatty acids, the mycolic acids. In order to investigate the adaptive changes in the mycolic acid composition, we investigated the composition of mycolic acids during the response both to osmotic stress caused by NaCl and to 4-chlorophenol in Rhodococcus opacus PWD4...
December 2016: AMB Express
Zhirong Li, Graham Peers, Rachel M Dent, Yong Bai, Scarlett Y Yang, Wiebke Apel, Lauriebeth Leonelli, Krishna K Niyogi
Plants, algae and cyanobacteria need to regulate photosynthetic light harvesting in response to the constantly changing light environment. Rapid adjustments are required to maintain fitness because of a trade-off between efficient solar energy conversion and photoprotection. The xanthophyll cycle, in which the carotenoid pigment violaxanthin is reversibly converted into zeaxanthin, is ubiquitous among green algae and plants and is necessary for the regulation of light harvesting, protection from oxidative stress and adaptation to different light conditions(1,2)...
2016: Nature Plants
Faisal Islam, Tahira Yasmeen, Muhammad Saleem Arif, Muhammad Riaz, Sher Muhammad Shahzad, Qaiser Imran, Irfan Ali
Heavy metal contamination of agricultural soil has become a serious global problem. This study was aimed to evaluate the effects of two chromium (Cr) tolerant plant growth promoting bacteria (PGPB) in combination with salicylic acid (SA) on plant growth, physiological, biochemical responses and heavy metal uptake under Cr contamination. A pot experiment (autoclaved sand as growing medium) was performed using maize (Zea mays L.) as a test crop under controlled conditions. Cr toxicity significantly reduced plant growth, photosynthetic pigment, carbohydrates metabolism and increased H2O2, MDA, relative membrane permeability, proline and Cr contents in maize leaves...
August 18, 2016: Plant Physiology and Biochemistry: PPB
Anna D Tischler, Rachel L Leistikow, Pavithra Ramakrishnan, Martin I Voskuil, John D McKinney
The Mycobacterium tuberculosis genome encodes two complete high-affinity Pst phosphate-specific transporters. We previously demonstrated that a membrane-spanning component of one Pst system, PstA1, was essential both for M. tuberculosis virulence and for regulation of gene expression in response to external phosphate availability. To determine if the alternative Pst system is similarly required for virulence or gene regulation, we constructed a deletion of pstA2. Transcriptome analysis revealed that PstA2 is not required for regulation of gene expression in phosphate-replete growth conditions...
2016: PloS One
Hirofumi Wada
Helices are ubiquitous in nature, and helical shape transition is often observed in residually stressed bodies, such as composites, wherein materials with different mechanical properties are glued firmly together to form a whole body. Inspired by a variety of biological examples, the basic physical mechanism responsible for the emergence of twisting and bending in such thin composite structures has been extensively studied. Here, we propose a simplified analytical model wherein a slender membrane tube undergoes a helical transition driven by the contraction of an elastic ribbon bound to the membrane surface...
September 21, 2016: Soft Matter
Joris van der Heijden, Lisa A Reynolds, Wanyin Deng, Allan Mills, Roland Scholz, Koshi Imami, Leonard J Foster, Franck Duong, B Brett Finlay
UNLABELLED: The outer membrane (OM) of Gram-negative bacteria provides protection against toxic molecules, including reactive oxygen species (ROS). Decreased OM permeability can promote bacterial survival under harsh circumstances and protects against antibiotics. To better understand the regulation of OM permeability, we studied the real-time influx of hydrogen peroxide in Salmonella bacteria and discovered two novel mechanisms by which they rapidly control OM permeability. We found that pores in two major OM proteins, OmpA and OmpC, could be rapidly opened or closed when oxidative stress is encountered and that the underlying mechanisms rely on the formation of disulfide bonds in the periplasmic domain of OmpA and TrxA, respectively...
2016: MBio
Riikka Keto-Timonen, Nina Hietala, Eveliina Palonen, Anna Hakakorpi, Miia Lindström, Hannu Korkeala
Bacteria have evolved a number of mechanisms for coping with stress and adapting to changing environmental conditions. Many bacteria produce small cold shock proteins (Csp) as a response to rapid temperature downshift (cold shock). During cold shock, the cell membrane fluidity and enzyme activity decrease, and the efficiency of transcription and translation is reduced due to stabilization of nucleic acid secondary structures. Moreover, protein folding is inefficient and ribosome function is hampered. Csps are thought to counteract these harmful effects by serving as nucleic acid chaperons that may prevent the formation of secondary structures in mRNA at low temperature and thus facilitate the initiation of translation...
2016: Frontiers in Microbiology
Galina V Smirnova, Aleksey V Tyulenev, Nadezda G Muzyka, Mikhail A Peters, Oleg N Oktyabrsky
An in-depth understanding of the physiological response of bacteria to antibiotic-induced stress is needed for development of new approaches to combatting microbial infections. Fluoroquinolone ciprofloxacin causes phase alterations in Escherichia coli respiration and membrane potential that strongly depend on its concentration. Concentrations lower than the optimal bactericidal concentration (OBC) do not inhibit respiration during the first phase. A dose higher than the OBC provokes immediate SOS-independent inhibition of respiration and growth that can contribute to a decreased SOS response and lowered susceptibility to high concentrations of ciprofloxacin...
August 4, 2016: Research in Microbiology
Dashuai Mu, Xiuxia Yu, Zhenxing Xu, Zongjun Du, Guanjun Chen
An increasing number of studies have investigated the effects of nanoparticles (NPs) on microbial systems; however, few existing reports have focused on the defense mechanisms of bacteria against NPs. Whether secondary metabolism biosynthesis is a response to NP stress and contributes to the adaption of bacteria to NPs is unclear. Here, a significant induction in the surfactin production and biofilm formation were detected by adding Al2O3 NPs to the B. subtilis fermentation broth. Physiological analysis showed that Al2O3 NP stress could also affect the cell and colony morphogenesis and inhibit the motility and sporulation...
2016: Scientific Reports
Anne-Catherine Raby, Chantal S Colmont, Ann Kift-Morgan, Jörg Köhl, Matthias Eberl, Donald Fraser, Nicholas Topley, Mario O Labéta
Peritoneal dialysis (PD) remains limited by dialysis failure due to peritoneal membrane fibrosis driven by inflammation caused by infections or sterile cellular stress. Given the fundamental role of Toll-like receptors (TLRs) and complement in inflammation, we assessed the potential of peritoneal TLR2, TLR4 and C5a receptors, C5aR and C5L2, as therapeutic targets in PD-associated fibrosis. We detected TLR2-, TLR4-, and C5aR-mediated proinflammatory and fibrotic responses to bacteria that were consistent with the expression of these receptors in peritoneal macrophages (TLR2/4, C5aR) and mesothelial cells (TLR2, C5aR)...
July 18, 2016: Journal of the American Society of Nephrology: JASN
Wael Elhenawy, Michael Bording-Jorgensen, Ezequiel Valguarnera, M Florencia Haurat, Eytan Wine, Mario F Feldman
UNLABELLED: Outer membrane vesicles (OMV) are proposed to mediate multiple functions during pathogenesis and symbiosis. However, the mechanisms responsible for OMV formation remain poorly understood. It has been shown in eukaryotic membranes that lipids with an inverted-cone shape favor the formation of positive membrane curvatures. Based on these studies, we formulated the hypothesis that lipid A deacylation might impose shape modifications that result in the curvature of the outer membrane (OM) and subsequent OMV formation...
2016: MBio
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