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stress response membrane bacteria

Casey Bryce, Mirita Franz-Wachtel, Nicolas Nalpas, Jennyfer Miot, Karim Benzerara, James M Byrne, Sara Kleindienst, Boris Macek, Andreas Kappler
The oxidation of Fe(II) by anoxygenic photosynthetic bacteria was likely a key contributor to Earth's biosphere prior to the evolution of oxygenic photosynthesis and is still found in a diverse range of modern environments. All known phototrophic Fe(II)-oxidizers can utilize a wide range of substrates thus making them very metabolically flexible. However, the underlying adaptations required to oxidize Fe(II), a potential stressor, are not completely understood. We used a combination of quantitative proteomics and cryogenic transmission electron microscopy (cryo-TEM) to compare cells of Rhodopseudomonas palustris TIE-1 grown photoautotrophically with Fe(II) or H2 , and photoheterotrophically with acetate...
June 18, 2018: Applied and Environmental Microbiology
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 have 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...
June 18, 2018: Journal of Bacteriology
Shaoqing Zhang, Binbin Sheng, Wenting Lin, Fangang Meng
Temperature is a well-known environmental stress that influences both microbial metabolism and community structure in the biological wastewater treatment systems. In this study, responses of biological performance and sludge microbiota to the long-term day/night temperature differences (DNTD) were investigated in membrane bioreactors (MBRs). The results showed that the functional bacteria could sustained their ecological functions at low DNTD (20/30 °C), resulting in relatively stable performance with respect to nutrient removal...
September 15, 2018: Science of the Total Environment
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...
June 9, 2018: Biochimica et Biophysica Acta
Cristina Faralla, Effie E Bastounis, Fabian E Ortega, Samuel H Light, Gabrielle Rizzuto, Salvatorre Nocadello, Wayne F Anderson, Jennifer R Robbins, Julie A Theriot, Anna I Bakardjiev
During pregnancy, the placenta protects the fetus against the maternal immune response, as well as bacterial and viral pathogens. Bacterial pathogens that have evolved specific mechanisms of breaching this barrier, such as Listeria monocytogenes, present a unique opportunity for learning how the placenta carries out its protective function. We previously identified the L. monocytogenes protein Internalin P (InlP) as a secreted virulence factor critical for placental infection. Here, we show that InlP, but not the highly similar L...
May 30, 2018: PLoS Pathogens
Tao Wei, Mussa Quareshy, Yu-Zhong Zhang, David J Scanlan, Yin Chen
In vast areas of the ocean, microbes must adapt to the availability of scarce nutrients and a key strategy for reducing the cellular phosphorus (P) quota is to remodel membranes by replacing phospholipids with non-P surrogate lipids. A metallophosphoesterase, PlcP, is essential for lipid remodelling in cosmopolitan marine bacteria of the Roseobacter (e.g. Phaeobacter sp. MED193) and SAR11 clades (e.g. Pelagibacter sp. HTCC7211) and transcription of plcP is known to be induced by P limitation. In order to better understand PlcP-mediated lipid remodelling, we sought to characterise PlcP for its metal ion requirement and to determine its selectivity for native bacterial phospholipids...
May 25, 2018: Applied and Environmental Microbiology
I-Chun Weng, Hung-Lin Chen, Tzu-Han Lo, Wei-Han Lin, Huan-Yuan Chen, Daniel K Hsu, Fu-Tong Liu
While glycans are generally displayed on the cell surface or confined within the lumen of organelles, they can become exposed to the cytosolic milieu upon disruption of organelle membrane by various stresses or pathogens. Galectins are a family of β-galactoside-binding animal lectins synthesized and predominantly localized in the cytosol. Recent research indicates that some galectins may act as "danger signal sensors" by detecting unusual exposure of glycans to the cytosol. Galectin-8 was shown to promote antibacterial autophagy by recognizing host glycans on ruptured vacuolar membranes and interacting with the autophagy adaptor protein NDP52...
June 1, 2018: Glycobiology
Ornella Mailén Ontañon, Claudia Landi, Alfonso Carleo, Assunta Gagliardi, Laura Bianchi, Paola Solange González, Elizabeth Agostini, Luca Bini
Acinetobacter guillouiae SFC 500-1A is an environmental bacterium able to efficiently co-remediate phenol and Cr(VI). To further understand the molecular mechanisms triggered in this strain during the bioremediation process, variations in the proteomic profile after treatment with phenol and phenol plus Cr(VI) were evaluated. The proteomic analysis revealed the induction of the β-ketoadipate pathway for phenol oxidation and the assimilation of degradation products through TCA cycle and glyoxylate shunt. Phenol exposure increased the abundance of proteins associated to energetic processes and ATP synthesis, but it also triggered cellular stress...
April 27, 2018: Journal of Hazardous Materials
Xinyu Hong, H Deborah Chen, Eduardo A Groisman
Lipid A is the innermost component of the lipopolysaccharide (LPS) molecules that occupy the outer leaflet of the outer membrane in Gram-negative bacteria. Lipid A is recognized by the host immune system and targeted by cationic antimicrobial compounds. In Salmonella enterica serovar Typhimurium, the phosphates of lipid A are chemically modified by enzymes encoded by targets of the transcriptional regulator PmrA. These modifications increase resistance to the cationic peptide antibiotic polymyxin B by reducing the negative charge of the LPS...
May 8, 2018: Science Signaling
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
Julian Roth, Matthias D Koch, Alexander Rohrbach
The wall-less, helical bacterial genus Spiroplasma has a unique propulsion system; it is not driven by propeller-like flagella but by a membrane-bound, cytoplasmic, linear motor that consists of a contractile chain of identical proteins spanning the entire cell length. By a coordinated spread of conformational changes of the proteins, kinks propagate in pairs along the cell body. However, the mechanisms for the initiation or delay of kinks and their coordinated spread remain unclear. Here, we show how we manipulate the initiation of kinks, their propagation velocities, and the time between two kinks for a single cell trapped in an optical line potential...
April 24, 2018: Biophysical Journal
Aurore Palud, Hélène Scornec, Jean-François Cavin, Hélène Licandro
Lactic acid bacteria (LAB) are associated with various plant, animal, and human niches and are also present in many fermented foods and beverages. Thus, they are subjected to several stress conditions and have developed advanced response mechanisms to resist, adapt, and grow. This work aimed to identify the genes involved in some stress adaptation mechanisms in LAB. For this purpose, global reverse genetics was applied by screening a library of 1287 Lactobacillus paracasei transposon mutants for mild monofactorial stresses...
2018: Frontiers in Microbiology
Hee Geun Park, Kwang Sik Lee, Bo Yeon Kim, Hyung Joo Yoon, Yong Soo Choi, Kyeong Yong Lee, Hu Wan, Jianhong Li, Byung Rae Jin
Honeybee (Apis mellifera) egg-yolk protein vitellogenin (Vg) plays roles in immunity, antioxidation, and life span beyond reproduction, but it also acts as an allergen Api m 12 in venom. Here we established antimicrobial and antioxidant roles of honeybee Vg in the body and venom. Using the cDNA encoding Vg identified from Asiatic honeybee (A. cerana) workers, recombinant A. cerana Vg (AcVg) protein of approximately 180 kDa was produced in baculovirus-infected insect cells. In A. cerana worker bees, AcVg was expressed in the fat body and venom gland and was present in the secreted venom...
August 2018: Developmental and Comparative Immunology
Yogesh Hooda, Trevor F Moraes
The surface of many Gram-negative bacteria contains lipidated protein molecules referred to as surface lipoproteins or SLPs. SLPs play critical roles in host immune evasion, nutrient acquisition and regulation of bacterial stress response, and have been extensively studied as vaccine antigens. The aim of this review is to summarize the recent studies that have investigated the biosynthetic and translocation pathways used by different bacterial species to deliver SLPs to the surface. We will specifically focus on Slam, a novel outer membrane protein first discovered in pathogenic Neisseria sp...
March 23, 2018: Current Opinion in Structural Biology
Yosef Fichman, Zsuzsa Koncz, Noam Reznik, Gad Miller, László Szabados, Katharina Kramer, Hirofumi Nakagami, Hillel Fromm, Csaba Koncz, Aviah Zilberstein
The evolutionary conserved family of Selenoproteins performs redox-regulatory functions in bacteria, archaea and eukaryotes. Among them, members of the SELENOPROTEIN O (SELO) subfamily are located in mammalian and yeast mitochondria, but their functions are thus far enigmatic. Screening of T-DNA knockout mutants for resistance to the proline analogue thioproline (T4C), identified mutant alleles of the plant SELO homologue in Arabidopsis thaliana. Absence of SELO resulted in a stress-induced transcriptional activation instead of silencing of mitochondrial proline dehydrogenase, and also high elevation of Δ(1)-pyrroline-5-carboxylate dehydrogenase involved in degradation of proline, thereby alleviating T4C inhibition and lessening drought-induced proline accumulation...
May 2018: Plant Science: An International Journal of Experimental Plant Biology
Laura Czech, Lucas Hermann, Nadine Stöveken, Alexandra A Richter, Astrid Höppner, Sander H J Smits, Johann Heider, Erhard Bremer
Fluctuations in environmental osmolarity are ubiquitous stress factors in many natural habitats of microorganisms, as they inevitably trigger osmotically instigated fluxes of water across the semi-permeable cytoplasmic membrane. Under hyperosmotic conditions, many microorganisms fend off the detrimental effects of water efflux and the ensuing dehydration of the cytoplasm and drop in turgor through the accumulation of a restricted class of organic osmolytes, the compatible solutes. Ectoine and its derivative 5-hydroxyectoine are prominent members of these compounds and are synthesized widely by members of the Bacteria and a few Archaea and Eukarya in response to high salinity/osmolarity and/or growth temperature extremes...
March 22, 2018: Genes
Santosh K Ghosh, Zhimin Feng, Hisashi Fujioka, Renate Lux, Thomas S McCormick, Aaron Weinberg
Human beta defensins (hBDs) are small cationic peptides, expressed in mucosal epithelia and important agents of innate immunity, act as antimicrobial and chemotactic agents at mucosal barriers. In this perspective, we present evidence supporting a novel strategy by which the oral bacterium Fusobacterium nucleatum induces hBDs and other antimicrobial peptides (AMPs) in normal human oral epithelial cells (HOECs) and thereby protects them from other microbial pathogens. The findings stress (1) the physiological importance of hBDs, (2) that this strategy may be a mechanism that contributes to homeostasis and health in body sites constantly challenged with bacteria and (3) that novel properties identified in commensal bacteria could, one day, be harnessed as new probiotic strategies to combat colonization of opportunistic pathogens...
2018: Frontiers in Microbiology
Rakshak Kumar, Vishal Acharya, Srijana Mukhia, Dharam Singh, Sanjay Kumar
Pseudomonas frederiksbergensis ERDD5:01 is a psychrotrophic bacteria isolated from the glacial stream flowing from East Rathong glacier in Sikkim Himalaya. The strain showed survivability at high altitude stress conditions like freezing, frequent freeze-thaw cycles, and UV-C radiations. The complete genome of 5,746,824 bp circular chromosome and a plasmid of 371,027 bp was sequenced to understand the genetic basis of its survival strategy. Multiple copies of cold-associated genes encoding cold active chaperons, general stress response, osmotic stress, oxidative stress, membrane/cell wall alteration, carbon storage/starvation and, DNA repair mechanisms supported its survivability at extreme cold and radiations corroborating with the bacterial physiological findings...
March 9, 2018: Genomics
Abhishek Mishra
Background: The genus Mycobacterium has an ability to persist in hostile environments for years before its reactivation in favorable conditions. The major bottleneck in decades of mycobacterial research is a poor understanding of molecular mechanism which assists bacteria to attain dormancy and reactivation later. Methods: In this study, hydroxyl radical was quantified in aerobically growing mycobacterial cells using 2-deoxy-D-ribose assay. Furthermore, extraneous addition of hydroxyl radical in Wayne's dormancy model induced reactivation of dormant cells...
January 2018: International Journal of Mycobacteriology
Victor Zarantonello, Thiago P Silva, Natália P Noyma, Juliana P Gamalier, Mariana M Mello, Marcelo M Marinho, Rossana C N Melo
Secretion of membrane-limited vesicles, collectively termed extracellular vesicles (EVs), is an important biological process of both eukaryotic and prokaryotic cells. This process has been observed in bacteria, but remains to be better characterized at high resolution in cyanobacteria. In the present work, we address the release of EVs by Cylindrospermopsis raciborskii (CYRF-01), a filamentous bloom-forming cyanobacterium, exposed to environmental stressors. First, non-axenic cultures of C. raciborskii (CYRF-01) were exposed to ultraviolet radiation (UVA + UVB) over a 6 h period, which is known to induce structural damage to this species...
2018: Frontiers in Microbiology
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