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https://www.readbyqxmd.com/read/28429713/gating-of-tonb-dependent-transporters-by-substrate-specific-forced-remodelling
#1
Samuel J Hickman, Rachael E M Cooper, Luca Bellucci, Emanuele Paci, David J Brockwell
Membrane proteins play vital roles in inside-out and outside-in signal transduction by responding to inputs that include mechanical stimuli. Mechanical gating may be mediated by the membrane or by protein(s) but evidence for the latter is scarce. Here we use force spectroscopy, protein engineering and bacterial growth assays to investigate the effects of force on complexes formed between TonB and TonB-dependent transporters (TBDT) from Gram-negative bacteria. We confirm the feasibility of protein-only mediated mechanical gating by demonstrating that the interaction between TonB and BtuB (a TBDT) is sufficiently strong under force to create a channel through the TBDT...
April 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28421167/iron-and-virulence-in-francisella-tularensis
#2
REVIEW
Girija Ramakrishnan
Francisella tularensis, the causative agent of tularemia, is a Gram-negative bacterium that infects a variety of cell types including macrophages, and propagates with great efficiency in the cytoplasm. Iron, essential for key enzymatic and redox reactions, is among the nutrients required to support this pathogenic lifestyle and the bacterium relies on specialized mechanisms to acquire iron within the host environment. Two distinct pathways for iron acquisition are encoded by the F. tularensis genome- a siderophore-dependent ferric iron uptake system and a ferrous iron transport system...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28397401/anaerobic-utilization-of-fe-iii-xenosiderophores-among-bacteroides-species-and-the-distinct-assimilation-of-fe-iii-ferrichrome-by-bacteroides-fragilis-within-the-genus
#3
Edson R Rocha, Anna S Krykunivsky
In this study, we show that Bacteroides species utilize Fe(III)-xenosiderophores as the only source of exogenous iron to support growth under iron-limiting conditions in vitro anaerobically. Bacteroides fragilis was the only species able to utilize Fe(III)-ferrichrome while Bacteroides vulgatus ATCC 8482 and Bacteroides thetaiotaomicron VPI 5482 were able to utilize both Fe(III)-enterobactin and Fe(III)-salmochelin S4 as the only source of iron in a dose-dependent manner. We have investigated the way B. fragilis assimilates Fe(III)-ferrichrome as initial model to understand the utilization of xenosiderophores in anaerobes...
April 11, 2017: MicrobiologyOpen
https://www.readbyqxmd.com/read/28352257/a-novel-pan-genome-reverse-vaccinology-approach-employing-a-negative-selection-strategy-for-screening-surface-exposed-antigens-against-leptospirosis
#4
LingBing Zeng, Dongliang Wang, NiYa Hu, Qing Zhu, Kaishen Chen, Ke Dong, Yan Zhang, YuFeng Yao, XiaoKui Guo, Yung-Fu Chang, YongZhang Zhu
Reverse vaccinology (RV) has been widely used for screening of surface-exposed proteins (PSEs) of important pathogens, including outer membrane proteins (OMPs), and extracellular proteins (ECPs) as potential vaccine candidates. In this study, we applied a novel RV negative strategy and a pan-genome analysis for screening of PSEs from 17 L. interrogans strains covering 11 predominately epidemic serovars and 17 multilocus typing (MLST) sequence types (STs) worldwide. Our results showed, for instance, out of a total of 633 predicted PSEs in strain 56601, 92...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28289030/antibiotic-prophylaxis-is-associated-with-subsequent-resistant-infections-in-children-with-an-initial-extended-spectrum-cephalosporin-resistant-enterobacteriaceae-infection
#5
Sibani Das, Amanda L Adler, Arianna Miles-Jay, Matthew P Kronman, Xuan Qin, Scott J Weissman, C A Burnham, Alexis Elward, Jason G Newland, Rangaraj Selvarangan, Kaede V Sullivan, Theoklis Zaoutis, Danielle M Zerr
The objective of this study was to assess the association between previous antibiotic use, particularly long-term prophylaxis, and occurrence of subsequent resistant infections in children with index infections due to extended-spectrum cephalosporin-resistant Enterobacteriaceae We also investigated the concordance of index and subsequent isolates. Extended-spectrum cephalosporin-resistant E. coli and Klebsiella spp. isolated from normally sterile sites of patients aged <22 years were collected along with associated clinical data from four freestanding pediatric centers...
March 13, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28276700/iron-acquisition-through-the-bacterial-transferrin-receptor
#6
Anastassia K Pogoutse, Trevor F Moraes
Transferrin is one of the sources of iron that is most readily available to colonizing and invading pathogens. In this review, we look at iron uptake by the bacterial transferrin receptor that is found in the families Neisseriaceae, Pasteurellaceae and Moraxellaceae. This bipartite receptor consists of the TonB-dependent transporter, TbpA, and the surface lipoprotein, TbpB. In the past three decades, major advancements have been made in our understanding of the mechanism through which the Tbps take up iron...
March 1, 2017: Critical Reviews in Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28264993/going-outside-the-tonb-box-identification-of-novel-fepa-tonb-interactions-in-vivo
#7
Michael G Gresock, Kathleen Postle
In Gram-negative bacteria, the cytoplasmic membrane protein TonB transmits energy derived from protonmotive force to energize transport of important nutrients through TonB-dependent transporters in the outer membrane. Each transporter consists of a beta-barrel domain and a lumen-occluding cork domain containing an essential sequence called the TonB box. To date, the only identified site of transporter-TonB interaction is between the TonB box and residues ∼158-162 of TonB. While the mechanism of ligand transport is a mystery, a current model based on site-directed spin labeling and molecular dynamics simulations is that, following ligand binding, the otherwise-sequestered TonB box extends into the periplasm for recognition by TonB, which mediates transport by pulling or twisting the cork...
March 6, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28264906/inactivation-of-nmb0419-encoding-a-sel1-like-repeat-slr-protein-in-neisseria-meningitidis-is-associated-with-differential-expression-of-genes-belonging-to-the-fur-regulon-and-reduced-intra-epithelial-replication
#8
Ming-Shi Li, Paul R Langford, J Simon Kroll
Neisseria meningitidis is a commensal microbe that colonizes the human nasopharynx but occasionally invades the bloodstream to cause life-threatening infection. N. meningitidis MC58 NMB0419 encodes a Sel1-like repeat (SLR)-containing protein, previously implicated in invasion of epithelial cells. A gene-regulatory function was revealed in Escherichia coli expressing plasmid-borne NMB0419 showing significantly increased epithelial adherence compared to wild type, due to increased expression of mannose-sensitive type 1 pili...
March 6, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28242720/fluorescence-high-throughput-screening-for-inhibitors-of-tonb-action
#9
Brittany L Nairn, Olivia S Eliasson, Dallas R Hyder, Noah J Long, Aritri Majumdar, Somnath Chakravorty, Peter McDonald, Anuradha Roy, Salete M Newton, Phillip E Klebba
Gram (-) bacteria acquire ferric siderophores through TonB-dependent outer membrane transporters (TBDT). By fluorescence spectroscopic high-throughput screening (FLHTS) we identified inhibitors of TonB-dependent ferric enterobactin (FeEnt) uptake through E. coli FepA (EcoFepA). Among 165 inhibitors found in a primary screen of 17,441 compounds, we evaluated 20 in secondary tests: TonB-dependent ferric siderophore uptake and colicin killing; proton-motive force-dependent lactose transport. 6 of 20 primary hits inhibited TonB activity in all tests...
February 27, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28242693/manganese-scavenging-and-oxidative-stress-response-mediated-by-type-vi-secretion-system-in-burkholderia-thailandensis
#10
Meiru Si, Chao Zhao, Brianne Burkinshaw, Bing Zhang, Dawei Wei, Yao Wang, Tao G Dong, Xihui Shen
Type VI secretion system (T6SS) is a versatile protein export machinery widely distributed in Gram-negative bacteria. Known to translocate protein substrates to eukaryotic and prokaryotic target cells to cause cellular damage, the T6SS has been primarily recognized as a contact-dependent bacterial weapon for microbe-host and microbial interspecies competition. Here we report contact-independent functions of the T6SS for metal acquisition, bacteria competition, and resistance to oxidative stress. We demonstrate that the T6SS-4 in Burkholderia thailandensis is critical for survival under oxidative stress and is regulated by OxyR, a conserved oxidative stress regulator...
March 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28230771/antibiotic-resistance-determinant-focused-acinetobacter-baumannii-vaccine-designed-using-reverse-vaccinology
#11
Zhaohui Ni, Yan Chen, Edison Ong, Yongqun He
As one of the most influential and troublesome human pathogens, Acinetobacter baumannii (A. baumannii) has emerged with many multidrug-resistant strains. After collecting 33 complete A. baumannii genomes and 84 representative antibiotic resistance determinants, we used the Vaxign reverse vaccinology approach to predict classical type vaccine candidates against A. baumannii infections and new type vaccine candidates against antibiotic resistance. Our genome analysis identified 35 outer membrane or extracellular adhesins that are conserved among all 33 genomes, have no human protein homology, and have less than 2 transmembrane helices...
February 21, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28213182/microbial-nickel-cellular-uptake-and-delivery-to-enzyme-centers
#12
REVIEW
Conor J Zeer-Wanklyn, Deborah B Zamble
Nickel enzymes allow microorganisms to access chemistry that can be vital for survival and virulence. In this review we highlight recent work on several systems that import nickel ions and deliver them to the active sites of these enzymes. Small molecules, in particular l-His and derivatives, may chelate nickel ions before import at TonB-dependent outer-membrane and ABC-type inner-membrane transporters. Inside the cell, nickel ions are used by maturation factors required to produce nickel enzymes such as [NiFe]-hydrogenase, urease and lactate racemase...
February 16, 2017: Current Opinion in Chemical Biology
https://www.readbyqxmd.com/read/28190743/a-medically-relevant-capsular-polysaccharide-in-acinetobacter-baumannii-is-a-potential-vaccine-candidate
#13
Feng-Ling Yang, Tze-Chi Lou, Shu-Chen Kuo, Wan-Ling Wu, Jeffy Chern, Yi-Tzu Lee, Shui-Tsung Chen, Wei Zou, Nien-Tsung Lin, Shih-Hsiung Wu
Concerns of Acinetobacter baumannii infection have increased due to the emergence of multi-drug resistance. In the present study, we determined the capsular polysaccharide (CPS) structure of A. baumannii SK44, a clinical isolate from Taiwan, to consist of pentasaccharide repeats. We found that CPS-induced antibody provided 55% protection against challenge in an animal model. The CPS-specific antibody reacted with the surface components of about 62% clinical isolates (342/554 strains) from cross-sectional and longitudinal studies by dot-immunoassay...
February 9, 2017: Vaccine
https://www.readbyqxmd.com/read/28137795/structure-and-function-of-the-piua-and-pira-siderophore-drug-receptors-from-pseudomonas-aeruginosa-and-acinetobacter-baumannii
#14
Lucile Moynié, Alexandre Luscher, Dora Rolo, Daniel Pletzer, Antoni Tortajada, Helge Weingart, Yvonne Braun, Malcolm G P Page, James H Naismith, Thilo Köhler
The outer membrane of Gram-negative bacteria presents an efficient barrier to the permeation of antimicrobial molecules. One strategy pursued to circumvent this obstacle is to hijack transport systems for essential nutrients, such as iron. BAL30072 and MC-1 are two monobactams conjugated to a dihydroxypyridone siderophore that are active against Pseudomonas aeruginosa and Acinetobacter baumannii Here, we investigated the mechanism of action of these molecules in A. baumannii We identified two novel TonB-dependent receptors, termed Ab-PiuA and Ab-PirA, that are required for the antimicrobial activity of both agents...
April 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28104383/virulence-traits-and-pathogenicity-of-uropathogenic-escherichia-coli-isolates-with-common-and-uncommon-o-serotypes
#15
Qingqing Gao, Debao Zhang, Zhengqin Ye, Xiaoping Zhu, Weixia Yang, Lanmei Dong, Song Gao, Xiufan Liu
Urinary tract infections (UTIs) are among the most common human diseases worldwide. This study aimed to collect uropathogenic Escherichia coli (UPEC) isolates from Jiangsu Province and obtain insights into the molecular epidemiology of UPEC in this region. The O serotypes, phylogenetic groups, and virulence factors of 183 UPEC isolates were determined. In this study, we isolated 51 UPEC isolates with common O serotypes including O1, O2, O4, O6, O7, O16, O18 and O75, as well as 35 of those with uncommonly encountered O serotypes including O8, O12, O15, O26, and O74...
March 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28083564/direct-heme-uptake-by-phytoplankton-associated-roseobacter-bacteria
#16
Shane L Hogle, Bianca Brahamsha, Katherine A Barbeau
Iron is an essential micronutrient and can limit the growth of both marine phytoplankton and heterotrophic bacterioplankton. In this study, we investigated the molecular basis of heme transport, an organic iron acquisition pathway, in phytoplankton-associated Roseobacter bacteria and explored the potential role of bacterial heme uptake in the marine environment. We searched 153 Roseobacter genomes and found that nearly half contained putative complete heme transport systems with nearly the same synteny. We also examined a publicly available coculture transcriptome and found that Roseobacter strain Sulfitobacter sp...
January 2017: MSystems
https://www.readbyqxmd.com/read/28077872/structural-basis-for-nutrient-acquisition-by-dominant-members-of-the-human-gut-microbiota
#17
Amy J Glenwright, Karunakar R Pothula, Satya P Bhamidimarri, Dror S Chorev, Arnaud Baslé, Susan J Firbank, Hongjun Zheng, Carol V Robinson, Mathias Winterhalter, Ulrich Kleinekathöfer, David N Bolam, Bert van den Berg
The human large intestine is populated by a high density of microorganisms, collectively termed the colonic microbiota, which has an important role in human health and nutrition. The survival of microbiota members from the dominant Gram-negative phylum Bacteroidetes depends on their ability to degrade dietary glycans that cannot be metabolized by the host. The genes encoding proteins involved in the degradation of specific glycans are organized into co-regulated polysaccharide utilization loci, with the archetypal locus sus (for starch utilisation system) encoding seven proteins, SusA-SusG...
January 19, 2017: Nature
https://www.readbyqxmd.com/read/28056815/comparative-genomics-of-host-adaptive-traits-in-xanthomonas-translucens-pv-graminis
#18
Lena Hersemann, Daniel Wibberg, Jochen Blom, Alexander Goesmann, Franco Widmer, Frank-Jörg Vorhölter, Roland Kölliker
BACKGROUND: Xanthomonas translucens pathovars differ in their individual host ranges among Poaceae. As the causal agent of bacterial wilt in Italian ryegrass (Lolium multiflorum Lam.), X. translucens pv. graminis (Xtg) is one of the most important bacterial pathogens in temperate grassland regions. The genomes of six Xtg strains from Switzerland, Norway, and New Zealand were sequenced in order to gain insight into conserved genomic traits from organisms covering a wide geographical range...
January 5, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28036380/two-component-signaling-system-vgrrs-directly-senses-extracytoplasmic-and-intracellular-iron-to-control-bacterial-adaptation-under-iron-depleted-stress
#19
Li Wang, Yue Pan, Zhi-Hui Yuan, Huan Zhang, Bao-Yu Peng, Fang-Fang Wang, Wei Qian
Both iron starvation and excess are detrimental to cellular life, especially for animal and plant pathogens since they always live in iron-limited environments produced by host immune responses. However, how organisms sense and respond to iron is incompletely understood. Herein, we reveal that in the phytopathogenic bacterium Xanthomonas campestris pv. campestris, VgrS (also named ColS) is a membrane-bound receptor histidine kinase that senses extracytoplasmic iron limitation in the periplasm, while its cognate response regulator, VgrR (ColR), detects intracellular iron excess...
December 2016: PLoS Pathogens
https://www.readbyqxmd.com/read/28035693/identification-of-a-u-zn-cu-responsive-global-regulatory-two-component-system-in-caulobacter-crescentus
#20
Dan M Park, K Wesley Overton, Megan J Liou, Yongqin Jiao
Despite the well-known toxicity of uranium (U) to bacteria, little is known about how cells sense and respond to U. The recent finding of a U-specific stress response in Caulobacter crescentus has provided a foundation for studying the mechanisms of U- perception in bacteria. To gain insight into this process, we used a forward genetic screen to identify the regulatory components governing expression of the urcA promoter (PurcA ) that is strongly induced by U. This approach unearthed a previously uncharacterized two-component system, named UzcRS, which is responsible for U-dependent activation of PurcA ...
December 30, 2016: Molecular Microbiology
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