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David N Bolam, Bert van den Berg
The lower human gastro-intestinal tract is inhabited by an extremely high density of micro-organisms, collectively termed the colonic microbiota. Just two bacterial phyla dominate this habitat, the Gram-positive Firmicutes and the Gram-negative Bacteroidetes. The colon is further characterised by a relative lack of small, easily accessible nutrients such as simple sugars, lipids and amino acids. Instead, a plethora of diet-derived and host polysaccharides constitute the main source of nutrients. Due to their size and complexity, the uptake of such glycans for metabolic utilisation is an energy-dependent process, which in Bacteroides spp...
March 15, 2018: Current Opinion in Structural Biology
Sajad Abdollahi, Iraj Rasooli, Seyed Latif Mousavi Gargari
Acinetobacter baumannii is an opportunistic multidrug resistant pathogen. TonB-dependent copper receptor is an outer membrane protein and has a role in binding of A. baumannii to host cell via attachment to fibronectin. Moreover, it is highly expressed in biofilm community. In this study the properties of copper receptor were analyzed in silico and its vaccine potential was investigated. TonB-dependent copper and iron receptor domains plus one plug domain at N-terminal were determined by domain analysis. Topology modeling showed 22 β-strands, 11 loops and 10 periplasmic turns...
March 7, 2018: Microbial Pathogenesis
Leah Schwiesow, Erin Mettert, Yahan Wei, Halie K Miller, Natalia G Herrera, David Balderas, Patricia J Kiley, Victoria Auerbuch
Despite the mammalian host actively sequestering iron to limit pathogenicity, heme (or hemin when oxidized) and hemoproteins serve as important sources of iron for many bloodborne pathogens. The HmuRSTUV hemin uptake system allows Yersinia species to uptake and utilize hemin and hemoproteins as iron sources. HmuR is a TonB-dependent outer membrane receptor for hemin and hemoproteins. HmuTUV comprise a inner membrane ABC transporter that transports hemin and hemoproteins from the periplasmic space into the bacterial cytoplasm, where it is degraded by HmuS...
2018: Frontiers in Cellular and Infection Microbiology
Sajad Abdollahi, Iraj Rasooli, Seyed Latif Mousavi Gargari
Acinetobacter baumannii is an opportunistic gram negative pathogen that can adhere to different surfaces and cause different nosocomial infections. To investigate the role of TonB-dependent copper receptor, an outer membrane protein, in virulence of A. baumannii, we deleted this receptor from A. baumannii chromosome. There was a significant decrease in biofilm formation by copper receptor deficient mutant strain. Similarly, the adherence to human epithelial cell and the hydrophobicity were declined. The survival rate of the mutant strain in human sera was reduced while no change was observed in motility of strains...
March 6, 2018: Infection, Genetics and Evolution
Grace E Kenney, Amy C Rosenzweig
Methanobactins (Mbns) are ribosomally produced, post-translationally modified natural products that bind copper with high affinity and specificity. Originally identified in methanotrophic bacteria, which have a high need for copper, operons encoding these compounds have also been found in many non-methanotrophic bacteria. The proteins responsible for Mbn biosynthesis include several novel enzymes. Mbn transport involves export through a multidrug efflux pump and re-internalization via a TonB-dependent transporter...
January 18, 2018: Journal of Biological Chemistry
Jessica L Sarver, Michael Zhang, Lishan Liu, David Nyenhuis, David S Cafiso
Bacterial outer membrane TonB-dependent transporters function by executing cycles of binding and unbinding to the inner membrane protein TonB. In the vitamin B12 transporter BtuB and the ferric citrate transporter FecA, substrate binding increases the periplasmic exposure of the Ton box, an energy-coupling segment. This increased exposure appears to enhance the affinity of the transporter for TonB. Here, continuous wave and pulse EPR spectroscopy were used to examine the state of the Ton box in the Escherichia coli ferrichrome transporter FhuA...
January 26, 2018: Biochemistry
Tally Rosenberg, Bolaji Babajide Salam, Saul Burdman
Acidovorax citrulli is the causal agent of bacterial fruit blotch of cucurbits. We have shown that functional type IV pili (T4P) are required for full virulence of this bacterium. To identify A. citrulli genes required for T4P activity, we screened a library of about 10,000 transposon mutants of A. citrulli strain M6 for altered T4P-mediated twitching motility. This screen led to the identification of 50 mutants impaired in twitching ability due to transposon insertions into 20 different genes. Representative mutants with disruptions in these genes were further characterized...
January 3, 2018: Molecular Plant-microbe Interactions: MPMI
Haiyuan Cai, Yonghui Zeng
Aquidulcibacter paucihalophilus TH1-2T is a member of the family Caulobacteraceae within Alphaproteobacteria isolated from cyanobacterial aggregates in a eutrophic lake. The draft genome comprises 3,711,627 bp and 3489 predicted protein-coding genes. The genome of strain TH1-2T has 270 genes encoding peptidases. And metallo and serine peptidases were found most frequently. A high number of genes encoding carbohydrate active enzymes (141 CAZymes) also present in strain TH1-2T genome. Among CAZymes, 47 glycoside hydrolase families, 37 glycosyl transferase families, 38 carbohydrate esterases families, nine auxiliary activities families, seven carbohydrate-binding modules families, and three polysaccharide lyases families were identified...
2017: Standards in Genomic Sciences
Fang-Fang Wang, Shou-Ting Cheng, Yao Wu, Bao-Zhen Ren, Wei Qian
Recognition of the host plant is a prerequisite for infection by pathogenic bacteria. However, how bacterial cells sense plant-derived stimuli, especially chemicals that function in regulating plant development, remains completely unknown. Here, we have identified a membrane-bound histidine kinase of the phytopathogenic bacterium Xanthomonas campestris, PcrK, as a bacterial receptor that specifically detects the plant cytokinin 2-isopentenyladenine (2iP). 2iP binds to the extracytoplasmic region of PcrK to decrease its autokinase activity...
December 5, 2017: Cell Reports
Sayak Bhattacharya, Jayanta Debabrata Choudhury, Ratan Gachhui, Joydeep Mukherjee
The primary pathogen of the Great Barrier Reef sponge Rhopaloeides odorabile, recently identified as a novel strain (NW4327) of Pseudoalteromonas agarivorans, produced collagenase which degraded R. odorabile skeletal fibers. We now report the collagenase of P. agarivorans as a metalloprotease which required Ca2+ and Zn2+ as cofactors. The collagenase was a TonB dependent receptor (TBDR) having a carboxypeptidase regulatory like domain (CRLD) in the N-terminal along with an outer membrane (OM) channel superfamily domain...
April 1, 2018: International Journal of Biological Macromolecules
Dong-Xu Li, Hao Zhang, Xiao-Huang Chen, Zhang-Xian Xie, Yong Zhang, Shu-Feng Zhang, Lin Lin, Feng Chen, Da-Zhi Wang
Interactions between bacteria and phytoplankton during bloom events are essential for both partners, which impacts their physiology, alters ambient chemistry and shapes ecosystem diversity. Here, we investigated the community structure and metabolic activities of free-living bacterioplankton in different blooming phases of a dinoflagellate Prorocentrum donghaiense using a metaproteomic approach. The Fibrobacteres-Chlorobi-Bacteroidetes group, Rhodobacteraceae, SAR11 and SAR86 clades contributed largely to the bacterial community in the middle-blooming phase while the Pseudoalteromonadaceae exclusively dominated in the late-blooming phase...
November 10, 2017: Environmental Microbiology
Matthew D Di Guglielmo, Dalal Tonb, Zhaoping He, Adebowale Adeyemi, Kenneth L van Golen
OBJECTIVE: Disruption of satiety signaling may lead to increased caloric intake and obesity. Uroguanylin, the intestinal hormone, travels as a precursor to the central nervous system where it activates guanylyl cyclase C (GUCY2C) and stimulates pro-satiety neurons. Rodent studies have demonstrated that (1) GUCY2C-knockout mice over-eat and have increased weight gain vs. wild-type mice; and (2) hyper-caloric obesity diminishes uroguanylin expression. We measured circulating plasma pro-uroguanylin, along with other gastrointestinal peptides and inflammatory markers, in human adolescents with and without obesity, as a pilot study...
November 3, 2017: Journal of Pediatric Gastroenterology and Nutrition
Kiyonobu Honma, Angela Ruscitto, Ashu Sharma
Tannerella forsythia and Fusobacterium nucleatum are dental plaque bacteria implicated in the development of periodontitis. These two species have been shown to form synergistic biofilms and found to be closely associated in dental plaque biofilms. A number of genetic loci for TonB-dependent membrane receptors (TDR) for glycan acquisition, with many existing in association with genes coding for enzymes involved in the breakdown of complex glycans, have been identified in T. forsythia In this study, we focused on a locus, BFO_0186 -- BFO_0188, that codes for a predicted TDR-SusD transporter along with a putative β-glucan hydrolyzing enzyme (BFO_0186)...
October 27, 2017: Applied and Environmental Microbiology
Paul White, Amar Joshi, Patrice Rassam, Nicholas G Housden, Renata Kaminska, Jonathan D Goult, Christina Redfield, Laura C McCaughey, Daniel Walker, Shabaz Mohammed, Colin Kleanthous
Unlike their descendants, mitochondria and plastids, bacteria do not have dedicated protein import systems. However, paradoxically, import of protein bacteriocins, the mechanisms of which are poorly understood, underpins competition among pathogenic and commensal bacteria alike. Here, using X-ray crystallography, isothermal titration calorimetry, confocal fluorescence microscopy, and in vivo photoactivatable cross-linking of stalled translocation intermediates, we demonstrate how the iron transporter FpvAI in the opportunistic pathogen Pseudomonas aeruginosa is hijacked to translocate the bacteriocin pyocin S2 (pyoS2) across the outer membrane (OM)...
November 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Jaime L Jensen, Qiong Wu, Christopher L Colbert
Outer membrane TonB-dependent transducers (TBDTs) actively transport ferric siderophore complexes from the extracellular environment into Gram-negative bacteria. They also participate in a cell-surface signaling regulatory pathway that results in upregulation of the transducer itself, in response to iron-deplete conditions. The TBDT PupB transports ferric pseudobactin, and signals through its N-terminal signaling domain (NTSD), while the TBDT homolog PupA is signaling-inactive. Here, we report the NMR chemical shift assignments of the PupB-NTSD...
October 25, 2017: Biomolecular NMR Assignments
Gonzalo A Pradenas, Julia N Myers, Alfredo G Torres
Burkholderia cenocepacia is an opportunistic pathogen prevalent in cystic fibrosis patients, which is particularly difficult to treat, causing chronic and eventually fatal infections. The lack of effective treatment options makes evident the need to develop alternative therapeutic or prophylactic approaches. Vaccines, and live attenuated vaccines, are an unexplored avenue to treat B. cenocepacia infections. Here we constructed and characterized a B. cenocepacia tonB mutant strain, which was unable to actively transport iron, to test whether this single gene deletion mutant (strain renamed GAP001) protected against an acute respiratory B...
September 28, 2017: Vaccines
Ziyang Dong, Shupan Guo, Huihui Fu, Haichun Gao
Shewanella oneidensis is among the first and the best studied bacteria capable of respiring minerals as terminal electron acceptors (EAs), including a variety of iron ores. This respiration process relies on a large number of c-type cytochromes, which per se are iron-containing proteins. Thus, iron plays an essential and special role in iron respiration of S. oneidensis, prompting extensive investigations into iron physiology. Despite this, we still know surprisingly little about the components and characteristics of iron transport in this bacterium...
September 18, 2017: Scientific Reports
Michael M Babykin, Tobias S A Obando, Vladislav V Zinchenko
In Gram-negative bacteria, transport of ferric siderophores through outer membrane is a complex process that requires specific outer membrane transporters and energy-transducing TonB-ExbB-ExbD system in the cytoplasmic membrane. The genome of the non-siderophore-producing cyanobacterium Synechocystis sp. PCC 6803 encodes all putative components of the siderophore-mediated iron uptake system. So far, there has been no experimental evidence for the existence of such a pathway in this organism. On the contrary, its reductive iron uptake pathway has been studied in detail...
September 12, 2017: Current Microbiology
Maria Chiara Mastropasqua, Melania D'Orazio, Mauro Cerasi, Francesca Pacello, Angelo Gismondi, Antonella Canini, Lorena Canuti, Ada Consalvo, Domenico Ciavardelli, Barbara Chirullo, Paolo Pasquali, Andrea Battistoni
Previous studies have suggested that P. aeruginosa possesses redundant zinc uptake systems. To identify uncharacterized zinc transporters, we analyzed the genome-wide transcriptional responses of P. aeruginosa PA14 to zinc restriction. This approach led to the identification of an operon (zrmABCD) regulated by the zinc uptake regulator Zur, that encodes for a metallophore-mediated zinc import system. This operon includes the genes for an uncharacterized TonB-dependent Outer Membrane Protein (ZrmA) and for a putative nicotianamine synthase (ZrmB)...
September 12, 2017: Molecular Microbiology
Andrea M Hujer, Paul G Higgins, Susan D Rudin, Genevieve L Buser, Steven H Marshall, Kyriaki Xanthopoulou, Harald Seifert, Laura J Rojas, T Nicholas Domitrovic, P Maureen Cassidy, Margaret C Cunningham, Robert Vega, Jon P Furuno, Christopher D Pfeiffer, Zintars G Beldavs, Meredith S Wright, Michael R Jacobs, Mark D Adams, Robert A Bonomo
Carbapenem antibiotics are among the mainstays for treating infections caused by Acinetobacter baumannii, especially in the Northwest United States, where carbapenem-resistant A. baumannii remains relatively rare. However, between June 2012 and October 2014, an outbreak of carbapenem-resistant A. baumannii occurred in 16 patients from five health care facilities in the state of Oregon. All isolates were defined as extensively drug resistant. Multilocus sequence typing revealed that the isolates belonged to sequence type 2 (international clone 2 [IC2]) and were >95% similar as determined by repetitive-sequence-based PCR analysis...
November 2017: Antimicrobial Agents and Chemotherapy
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