Linlin Hu, Chenchen Wang, Wenjia Lu, Hao Lu, Huanchun Chen, Chen Tan
The two-component system BaeSR is an extra-cytoplasmic stress response system in Escherichia coli, whose function is to be adapted to environmental stress. Recently, we have identified an active type VI secretion system in porcine extra-intestinal pathogenic Escherichia coli PCN033. DNA-protein interactions shows that BaeR directly binds to the promoter region of the T6SS and then induces its expression. Deletion of baeR/baeSR decreased zinc resistance of bacteria. Moreover, T6SS mutant Δhcp1/hcp2/hcp3 is more sensitive than wild type after exposure to external zinc, and complementation of hcp1 largely restored growth defect...
June 27, 2020: Microbial Pathogenesis
Ruth E Hernandez, Ramses Gallegos-Monterrosa, Sarah J Coulthurst
The Type VI secretion system (T6SS) is a protein translocation nanomachine widespread amongst Gram-negative bacteria and used as a means to deliver effectors directly into target bacterial or eukaryotic cells. These effectors have a wide variety of functions within target cells which ultimately help the secreting cell gain a competitive fitness advantage. Here we discuss the different ways in which these effectors can be delivered by the T6SS and the diverse mechanisms by which they exert their noxious action upon recipient cells...
June 27, 2020: Cellular Microbiology
Avatar Joshi, Samar A Mahmoud, Soo-Kyoung Kim, Justyne L Ogdahl, Vincent T Lee, Peter Chien, Fitnat H Yildiz
The LonA (or Lon) protease is a central post-translational regulator in diverse bacterial species. In Vibrio cholerae, LonA regulates a broad range of behaviors including cell division, biofilm formation, flagellar motility, c-di-GMP levels, the type VI secretion system (T6SS), virulence gene expression, and host colonization. Despite LonA's role in cellular processes critical for V. cholerae's aquatic and infectious life cycles, relatively few LonA substrates have been identified. LonA protease substrates were therefore identified through comparison of the proteomes of wild-type and ΔlonA strains following translational inhibition...
June 26, 2020: PLoS Genetics
Ching-Fang Chien, Cheng-Ying Liu, Yew-Yee Lu, You-Hsing Sung, Kuo-Yau Chen, Nai-Chun Lin
The type VI secretion system (T6SS) is a widespread bacterial nanoweapon used for delivery of toxic proteins into cell targets and contributes to virulence, anti-inflammatory processes, and interbacterial competition. In the model phytopathogenic bacterium Pseudomonas syringae pv. tomato ( Pst ) DC3000, two T6SS gene clusters, HSI-I and HSI-II, were identified, but their functions remain unclear. We previously reported that hcp2 , located in HSI-II, is involved in competition with enterobacteria and yeast. Here, we demonstrated that interbacterial competition of Pst DC3000 against several Gram-negative plant-associated bacteria requires mainly HSI-II activity...
2020: Frontiers in Microbiology
Stephanie Sibinelli-Sousa, Julia T Hespanhol, Gianlucca G Nicastro, Bruno Y Matsuyama, Stephane Mesnage, Ankur Patel, Robson F de Souza, Cristiane R Guzzo, Ethel Bayer-Santos
Type VI secretion systems (T6SSs) are nanomachines used by bacteria to inject toxic effectors into competitors. The identity and mechanism of many effectors remain unknown. We characterized a Salmonella T6SS antibacterial effector called Tlde1 that is toxic in target-cell periplasm and is neutralized by its cognate immunity protein (Tldi1). Microscopy analysis reveals that cells expressing Tlde1 stop dividing and lose cell envelope integrity. Bioinformatic analysis uncovers similarities between Tlde1 and the catalytic domain of l,d-transpeptidases...
June 23, 2020: Cell Reports
Federico M Ruiz, Juvenal Lopez, C Gastón Ferrara, Elena Santillana, Yanis R Espinosa, Mario F Feldman, Antonio Romero
The type VI secretion system (T6SS) is a complex molecular nanomachine used by Gram-negative bacteria to deliver diverse effectors into adjacent cells. A membrane complex (MC) anchors this transport system to the bacterial cell wall. One of the proteins forming the MC is TssL, a cytoplasmic protein bound to the inner membrane through a single transmembrane helix. Here, we report the structure of the cytoplasmic N-terminal region of TssL from Acinetobacter baumannii , a bacteria encoding in a single locus a secretion system that is a special case among others T6SSs...
June 22, 2020: Journal of Bacteriology
Rebecca M Kochanowsky, Christine Bradshaw, Isabel Forlastro, S Patricia Stock
Xenorhabdus bovienii strain jolietti (XBJ) is a Gram-negative bacterium that interacts with several organisms as a part of its life cycle. It is a beneficial symbiont of nematodes, a potent pathogen of a wide range of soil-dwelling insects, and also has the ability to kill soil- and insect-associated microbes. Entomopathogenic Steinernema nematodes vector XBJ into insects, releasing the bacteria into the insect body cavity. There, XBJ produce a variety of insecticidal toxins and antimicrobials. XBJ's genome also encodes two separate Type Six Secretion Systems (T6SSs), structures that allow bacteria to inject specific proteins directly into other cells, but their roles in the XBJ life cycle are mostly unknown...
June 19, 2020: FEMS Microbiology Ecology
Fatima Kamal, Xiaoye Liang, Kevin Manera, Tong-Tong Pei, Haeun Kim, Linh G Lam, Alexander Pun, Steven J Hersch, Tao G Dong
The type VI secretion system (T6SS) is a lethal microbial weapon that injects a large needle-like structure carrying toxic effectors into recipient cells through physical penetration. How recipients respond to physical force and effectors remains elusive. Here, we use a series of effector mutants of Vibrio cholerae to determine how T6SS elicits response in Pseudomonas aeruginosa and Escherichia coli. We show that TseL, but no other effectors or physical puncture, triggers the tit-for-tat response of P. aeruginosa H1-T6SS...
June 16, 2020: Cell Reports
Liming Zheng, Shenghua Wang, Mengyu Ling, Zhengmei Lv, Shuai Lin
Hemolysin-coregulated protein (Hcp) of Salmonella enteritidis is known to be a structural and effector protein of the T6SS, but little is known about the role of Hcp in host cells. In this study, Hcp was expressed by plasmid pEGFP-N1-hcp in BHK-21 cells and the results showed that the subcellular localization of Hcp was predominantly in the cytoplasm of BHK-21 cells. When Hcp was over-expressed by transfecting plasmid pCI-neo-hcp in BHK-21 cells and mRNA sequencing was performed to analyze differentially expressed genes, the results showed a change in the expression levels of 307 mRNAs (fold change > 2, and p  < 0...
July 2020: 3 Biotech
Yanqi Li, Lin Chen, Pansong Zhang, Anjali Y Bhagirath, Kangmin Duan
The type VI secretion system (T6SS) is a toxic effector delivery apparatus widely distributed in Gram-negative bacteria. The opportunistic pathogen Pseudomonas aeruginosa encodes three T6SSs, namely H1-, H2-, and H3-T6SS. Each T6SS possesses its own effectors and their roles are not yet fully understood. Here, we report that an H3-T6SS deletion mutant PAO1(Δ clpV3 ) significantly affected the virulence-related phenotypes including pyocyanin production, biofilm formation, proteolytic activity, and motilities...
2020: Frontiers in Microbiology
Yeounju Choi, Namgyu Kim, Mohamed Mannaa, Hongsup Kim, Jungwook Park, Hyejung Jung, Gil Han, Hyun-Hee Lee, Young-Su Seo
Type VI secretion system (T6SS) is a contact-dependent secretion system, employed by most gram-negative bacteria for translocating effector proteins to target cells. The present study was conducted to investigate T6SS in Xanthomonas oryzae pv. oryzae ( Xoo ), which causes bacterial blight in rice, and to unveil its functions. Two T6SS clusters were found in the genome of Xoo PXO99A . The deletion mutants, Δ hcp 1, Δ hcp 2, and Δ hcp 12, targeting the hcp gene in each cluster, and a double-deletion mutant targeting both genes were constructed and tested for growth rate, pathogenicity to rice, and inter-bacterial competition ability...
June 1, 2020: Plant Pathology Journal
Kayley H Janssen, Jodi M Corley, Louise Djapgne, J T Cribbs, Deven Voelker, Zachary Slusher, Robert Nordell, Elizabeth E Regulski, Barbara I Kazmierczak, Emily Williams McMackin, Timothy L Yahr
Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen causing skin and soft tissue, respiratory, and bloodstream infections. The type III secretion system (T3SS) is one important virulence factor. Production of the T3SS is controlled by ExsA, a transcription factor that activates expression of the entire T3SS regulon. Global regulators including Vfr, RsmA, and Hfq also contribute to regulation of the T3SS. Vfr is a cAMP-responsive transcription factor that activates exsA transcription. RsmA, an RNA-binding protein, inversely controls expression of the T3SS and the type VI secretion system (T6SS)...
June 16, 2020: MBio
Cameron L Hubert, Stephen Li Michell
With the rapid increase of aquaculture contributing to sustainable food security, comes the need to better understand seafood associated diseases. One of the major aquatic bacterial genera responsible for human infections from seafood is Vibrio, especially from oysters. Currently, in vivo study of bacterial interactions within oysters is limited by the inability to promote high-level uptake of bacteria by oysters. This study has therefore evolved current natural marine snow protocols to generate 'artificial' marine snow, into which bacteria can be incorporated to facilitate extensive uptake by oysters...
June 9, 2020: Environmental Microbiology
Ursula Hofer
No abstract text is available yet for this article.
June 8, 2020: Nature Reviews. Microbiology
See-Yeun Ting, Esteban Martínez-García, Shuo Huang, Savannah K Bertolli, Katherine A Kelly, Kevin J Cutler, Elizabeth D Su, Hui Zhi, Qing Tang, Matthew C Radey, Manuela Raffatellu, S Brook Peterson, Víctor de Lorenzo, Joseph D Mougous
Selective and targeted removal of individual species or strains of bacteria from complex communities can be desirable over traditional, broadly acting antibacterials in several contexts. However, generalizable strategies that accomplish this with high specificity have been slow to emerge. Here we develop programmed inhibitor cells (PICs) that direct the potent antibacterial activity of the type VI secretion system (T6SS) against specified target cells. The PICs express surface-displayed nanobodies that mediate antigen-specific cell-cell adhesion to effectively overcome the barrier to T6SS activity in fluid conditions...
August 12, 2020: Cell Host & Microbe
William P J Smith, Andrea Vettiger, Julius Winter, Till Ryser, Laurie E Comstock, Marek Basler, Kevin R Foster
The type VI secretion system (T6SS) is a nanomachine used by many bacteria to drive a toxin-laden needle into other bacterial cells. Although the potential to influence bacterial competition is clear, the fitness impacts of wielding a T6SS are not well understood. Here we present a new agent-based model that enables detailed study of the evolutionary costs and benefits of T6SS weaponry during competition with other bacteria. Our model identifies a key problem with the T6SS. Because of its short range, T6SS activity becomes self-limiting, as dead cells accumulate in its way, forming "corpse barriers" that block further attacks...
May 2020: PLoS Biology
Shuiyan Ma, Yuhao Dong, Nannan Wang, Jin Liu, Chengping Lu, Yongjie Liu
The type VI secretion system (T6SS) is a multiprotein weapon that kills eukaryotic predators or prokaryotic competitors by delivering toxic effectors. Despite the importance of T6SS in bacterial environmental adaptation, it is still challenging to systematically identify T6SS effectors because of their high diversity and lack of conserved domains. In this report, we discovered a putative effector gene, U876-17730, in the whole genome of Aeromonas hydrophila NJ-35 based on the reported conservative domain DUF4123 (domain of unknown function), with two cognate immunity proteins encoded downstream...
May 24, 2020: Veterinary Research
Cristian D Loaiza, Naveen Duhan, Matthew Lister, Rakesh Kaundal
The aerobic, Gram-negative motile bacillus, Burkholderia pseudomallei is a facultative intracellular bacterium causing melioidosis, a critical disease of public health importance, which is widely endemic in the tropics and subtropical regions of the world. Melioidosis is associated with high case fatality rates in animals and humans; even with treatment, its mortality is 20-50%. It also infects plants and is designated as a biothreat agent. B. pseudomallei is pathogenic due to its ability to invade, resist factors in serum and survive intracellularly...
May 23, 2020: Briefings in Bioinformatics
Jaime Vazquez-Lopez, Fernando Navarro-Garcia
Shiga-toxin-producing Escherichia coli (STEC) has become an important pathogen that can cause diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS) in humans. Recent reports show that the type VI secretion system (T6SS) from EHEC is required to produce infection in a murine model and its expression has been related to a higher prevalence of HUS. In this work, we use bioinformatics analyses to identify the core genes of the T6SS and compared the differences between these components among the two published genomes for EHEC O157:H7 strain EDL933...
2020: Frontiers in Cellular and Infection Microbiology
Areeqa Mustafa, Muhammad Ibrahim, Muhammad Asif Rasheed, Sumaira Kanwal, Annam Hussain, Asma Sami, Raza Ahmed, Zhu Bo
Enterobacter cloacae complex (Ecc) species are widely distributed opportunistic pathogens mainly associated with humans and plants. In this study, the genomes of clinical isolates including E. hormaechei, E. kobei, and E. ludwigii and non-clinical isolate including E. nimipressuralis were analysed in combination with the genome of E. asburiae by using the reference strain E. cloacae subsp. cloacae ATCC 13047; the Ecc strains were tested on artificial sputum media (ASM), which mimics the host, to evaluate T6SS genes as a case study...
May 18, 2020: Scientific Reports
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