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Bacteria secretion system

Hangjun Sun, Lili Shen, Yuanxia Qin, Xiaowei Liu, Kaiqiang Hao, Ying Li, Jie Wang, Jinguang Yang, Fenglong Wang
Chloride channel (CLC) proteins are important anion transporters conserved in organisms ranging from bacteria and yeast to plants and animals. According to sequence comparison, some plant CLCs are predicted to function as Cl- /H+ antiporters, but not Cl- channels. However, no direct evidence was provided to verify the role of these plant CLCs in regulating the pH of the intracellular compartment. We identified tobacco CLC-Nt1 interacting with the Potato virus Y (PVY) 6K2 protein. To investigate its physiological function, homologous genes of CLC-Nt1 in Nicotiana benthamiana were knocked out using the CRISPR/Cas9 system...
July 19, 2018: New Phytologist
Jonida Toska, Brian T Ho, John J Mekalanos
The type 6 secretion system (T6SS) is a nanomachine used by many Gram-negative bacteria, including Vibrio cholerae , to deliver toxic effector proteins into adjacent eukaryotic and bacterial cells. Because the activity of the T6SS is dependent on direct contact between cells, its activity is limited to bacteria growing on solid surfaces or in biofilms. V. cholerae can produce an exopolysaccharide (EPS) matrix that plays a role in adhesion and biofilm formation. In this work, we investigated the effect of EPS production on T6SS activity between cells...
July 18, 2018: Proceedings of the National Academy of Sciences of the United States of America
Arun A Gupta, Ines Reinartz, Gogulan Karunanithy, Alessandro Spilotros, Venkateswara Rao Jonna, Anders Hofer, Dmitri I Svergun, Andrew J Baldwin, Alexander Schug, Magnus Wolf-Watz
Bacterial virulence is typically initiated by translocation of effector or toxic proteins across host cell membranes. A class of Gram-negative pathogenic bacteria including Yersinia pseudotuberculosis and Yersinia pestis accomplishes this objective with a protein assembly called the Type III secretion system (T3SS). Yersinia effector proteins (Yop) are presented to the translocation apparatus through formation of specific complexes with their cognate chaperones (Syc). In the complexes where the structure is available, the Yops are extended and wrap around their cognate chaperone...
July 15, 2018: Journal of Molecular Biology
Eliana De Gregorio, Eliana Pia Esposito, Raffaele Zarrilli, Pier Paolo Di Nocera
Bacterial contact-dependent growth inhibition (CDI) systems are two-partner secretion systems in which toxic CdiA proteins are exported on the outer membrane by cognate transporter CdiB proteins. Upon binding to specific receptors, the C-terminal toxic (CT) domain, detached from CdiA, is delivered to neighbouring cells. Contacts inhibit the growth of not-self-bacteria, lacking immunity proteins co-expressed with CdiA, but promote cooperative behaviours in "self" bacteria, favouring the formation of biofilm structures...
July 17, 2018: Current Microbiology
Disha Srivastava, Jin Seo, Binayak Rimal, Sung Joon Kim, Stephanie Zhen, Andrew J Darwin
Carboxy-terminal processing proteases (CTPs) occur in all three domains of life. In bacteria, some of them have been associated with virulence. However, the precise roles of bacterial CTPs are poorly understood, and few direct proteolytic substrates have been identified. One bacterial CTP is the CtpA protease of Pseudomonas aeruginosa , which is required for type III secretion system (T3SS) function and for virulence in a mouse model of acute pneumonia. Here, we have investigated the function of CtpA in P. aeruginosa and identified some of the proteins it cleaves...
July 17, 2018: MBio
Junya Kato, Supratim Dey, Jose E Soto, Carmen Butan, Mason C Wilkinson, Roberto N De Guzman, Jorge E Galan
Type III protein secretion systems (T3SS) are encoded by several pathogenic or symbiotic bacteria. The central component of this nanomachine is the needle complex. Here we show in a Salmonella Typhimurium T3SS that assembly of the needle filament of this structure requires OrgC, a protein encoded within the T3SS gene cluster. Absence of OrgC results in significantly reduced number of needle substructures but does not affect needle length. We show that OrgC is secreted by the T3SS and that exogenous addition of OrgC can complement a ∆orgC mutation...
July 17, 2018: ELife
Patrycja Głowacka, Dorota Żakowska, Katarzyna Naylor, Marcin Niemcewicz, Agata Bielawska-Drózd
Brucellae are Gram-negative, small rods infecting mammals and capable of causing disease called brucellosis. The infection results in abortion and sterility in domestic animals (sheeps, pigs, rams etc). Especially dangerous for humans are: Brucella melitensis, Brucella suis, Brucella abortus, and Brucella canis that trigger unspecific symptoms (flu-like manifestation). Brucella rods are introduced via host cells, by inhalation, skin abrasions, ingestion or mucosal membranes. The most important feature of Brucella is the ability to survive and multiply within both phagocytic and non-phagocytic cells...
June 30, 2018: Polish Journal of Microbiology
Xiaopan Gao, Zhixia Mu, Xia Yu, Bo Qin, Justyna Wojdyla, Meitian Wang, Sheng Cui
Gram-negative bacteria utilize the type III secretion system (T3SS) to inject effector proteins into the host cell cytoplasm, where they subvert cellular functions and assist pathogen invasion. The conserved type III-associated ATPase is critical for the separation of chaperones from effector proteins, the unfolding of effector proteins and translocating them through the narrow channel of the secretion apparatus. However, how ATP hydrolysis is coupled to the mechanical work of the enzyme remains elusive. Herein, we present a complete description of nucleoside triphosphate binding by surface presentation antigens 47 (Spa47) from Shigella flexneri , based on crystal structures containing ATPγS, a catalytic magnesium ion and an ordered water molecule...
2018: Frontiers in Microbiology
David R Sannino, Clifford E Kraft, Katie A Edwards, Esther R Angert
Thiamin is essential to life, as it serves as a cofactor for enzymes involved in critical carbon transformations. Many bacteria can synthesize thiamin, while thiamin auxotrophs must obtain it or its precursors from the environment. Thiaminases degrade thiamin by catalyzing the base-exchange substitution of thiazole with a nucleophile, and thiaminase I specifically has been implicated in thiamin deficiency syndromes in animals. The biological role of this secreted enzyme has been a long-standing mystery. We used the thiaminase I producing soil bacterium Burkholderia thailandensis as a model to ascertain its function...
July 13, 2018: Applied and Environmental Microbiology
Chiara Rapisarda, Matteo Tassinari, Francesca Gubellini, Remi Fronzes
Bacterial secretion systems are responsible for releasing macromolecules to the extracellular milieu or directly into other cells. These membrane complexes are associated with pathogenicity and bacterial fitness. Understanding of these large assemblies has exponentially increased in the last few years thanks to electron microscopy. In fact, a revolution in this field has led to breakthroughs in characterizing the structures of secretion systems and other macromolecular machineries so as to obtain high-resolution images of complexes that could not be crystallized...
July 13, 2018: Annual Review of Microbiology
Anna Lucia Tornesello, Luigi Buonaguro, Maria Lina Tornesello, Franco Maria Buonaguro
The epithelium of the gastrointestinal tract is densely populated by complex microbial communities which exert both local and distant effects in the human body with relevant consequences on the metabolic status, immune system and overall health. A dynamic equilibrium between the many bacterial species and the host intestinal epithelium is maintained through the release of a large number of small molecules and peptides. The quorum sensing peptides are mainly secreted by Gram-positive bacteria and are able to "communicate" with human cells...
July 12, 2018: Mini Reviews in Medicinal Chemistry
Natalie J Bitto, Paul J Baker, Jennifer K Dowling, Georgie Wray-McCann, Amanda De Paoli, Le Son Tran, Pak Ling Leung, Katryn J Stacey, Ashley Mansell, Seth L Masters, Richard L Ferrero
Outer membrane vesicles (OMVs) are constitutively produced by Gram-negative bacteria both in vivo and in vitro. These lipid-bound structures carry a range of immunogenic components derived from the parent cell, which are transported into host target cells and activate the innate immune system. Recent advances in the field have shed light on some of the multifaceted roles of OMVs in host-pathogen interactions. In this study, we investigated the ability of OMVs from two clinically important pathogens, Pseudomonas aeruginosa and Helicobacter pylori, to activate canonical and non-canonical inflammasomes...
July 12, 2018: Immunology and Cell Biology
Zhouqi Cui, Xiaochen Yuan, Ching-Hong Yang, Regan B Huntley, Weimin Sun, Jie Wang, George W Sundin, Quan Zeng
Dickeya dadantii is a bacterial plant pathogen that causes soft rot disease on a wide range of host plants. The type III secretion system (T3SS) is an important virulence factor in D. dadantii . Expression of the T3SS is induced in the plant apoplast or in hrp -inducing minimal medium (hrp-MM), and is repressed in nutrient-rich media. Despite the understanding of induction conditions, how individual cells in a clonal bacterial population respond to these conditions and modulate T3SS expression is not well understood...
2018: Frontiers in Microbiology
Qinglin Fang, Wenlai Xu, Gonghan Xia, Zhicheng Pan
The aim of this study was to improve the removal of nitrogen pollutants from artificial sewage by a modeled two-stage constructed rapid infiltration (CRI) system. The C/N ratio of the second stage influent was elevated by addition of glucose. When the C/N ratio was increased to 5, the mean removal efficiency of total nitrogen (TN) reached up to 75.4%. Under this condition, the number of denitrifying bacteria in the permanently submerged denitrifying section (the second stage) was 22 times higher than that in the control experiment without added glucose...
July 12, 2018: International Journal of Environmental Research and Public Health
Inga-Maria Frick, Oonagh Shannon, Ariane Neumann, Christofer Karlsson, Mats Wikström, Lars Björck
Some strains of the bacterial pathogen Streptococcus pyogenes secrete protein SIC (streptococcal inhibitor of complement), including strains of the clinically relevant M1 serotype. SIC neutralizes the effect of a number of antimicrobial proteins/peptides and interferes with function of the host complement system. Previous studies have shown that some S. pyogenes proteins bind and modulate coagulation and fibrinolysis factors, raising the possibility that SIC also may interfere with the activity of these factors...
July 12, 2018: Journal of Biological Chemistry
Daniel F Rojas-Tapias, John D Helmann
Spx is a global transcriptional regulator present in low-GC Gram-positive bacteria, including the model bacterium Bacillus subtilis and various human pathogens. In B. subtilis, activation of Spx occurs in response to disulfide stress. We recently reported, however, that induction of Spx also occurs in response to cell wall stress, and that the molecular events that result in its activation under both stress conditions are mechanistically different. Here, we demonstrate that, in addition to up-regulation of spx transcription through the alternative sigma factor σM, full and timely activation of Spx-regulated genes by cell wall stress requires Spx stabilization by the anti-adaptor protein YirB...
July 12, 2018: PLoS Genetics
Alexandre B Pigozzo, Dominique Missiakas, Sergio Alonso, Rodrigo W Dos Santos, Marcelo Lobosco
In some bacterial infections, the immune system cannot eliminate the invading pathogen. In these cases, the invading pathogen is successful in establishing a favorable environment to survive and persist in the host organism. For example, S. aureus bacteria survive in organ tissues employing a set of mechanisms that work in a coordinated and highly regulated way allowing: (1) efficient impairment of the immune response; and (2) protection from the immune cells and molecules. S. aureus secretes several proteins including coagulases and toxins that drive abscess formation and persistence...
2018: Frontiers in Microbiology
Joana G Lopes, Victor Sourjik
The microorganisms in the gastrointestinal (GI) tract can influence the metabolism, immunity, and behavior of animal hosts. Increasing evidence suggests that communication between the host and the microbiome also occurs in the opposite direction, with hormones and other host-secreted compounds being sensed by microorganisms. Here, we addressed one key aspect of the host-microbe communication by studying chemotaxis of a model commensal bacterium, Escherichia coli, to several compounds present abundantly in the GI tract, namely catecholamines, thyroid hormones, and polyamines...
July 11, 2018: ISME Journal
Chih-Feng Wu, Delaney A Smith, Erh-Min Lai, Jeff H Chang
The bacterial type VI secretion system (T6SS) is a contractile nanomachine dedicated to delivering molecules out of bacterial cells. T6SS-encoding loci are in the genome sequences of many Gram-negative bacteria, and T6SS has been implicated in a plethora of roles. In the majority of cases, the T6SSs deliver effector proteins in a contact-dependent manner to antagonize other bacteria. Current models suggest that the effectors are deployed to influence social interactions in microbial communities. In this chapter, we describe the structure, function, and regulation of the T6SS and its effectors...
July 11, 2018: Current Topics in Microbiology and Immunology
Kwok Ho Lam, Chaolun Xue, Kailei Sun, Huawei Zhang, Wendy Wai Ling Lam, Zeyu Zhu, Juliana Tsz Yan Ng, William E Sause, Paphavee Lertsethtakarn, Kwok-Fai Lau, Karen M Ottemann, Shannon Wing Ngor Au
Bacterial flagella are rotary nano-machines that contribute to bacterial fitness in many settings, including host colonization. The flagellar motor relies on the multiprotein flagellar motor-switch complex to govern flagellum formation and rotational direction. Different bacteria exhibit great diversity in their flagellar motors. One such variation is exemplified by the motor-switch apparatus of the gastric pathogen Helicobacter pylori , which carries an extra switch protein, FliY, along with the more typical FliG, FliM, and FliN proteins...
July 10, 2018: Journal of Biological Chemistry
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