scholarly journals Population dynamics and transcriptomic responses ofPseudomonas aeruginosain a complex laboratory microbial community

2018 ◽  
Author(s):  
Yingying Cheng ◽  
Joey Kuok Hoong Yam ◽  
Zhao Cai ◽  
Yichen Ding ◽  
Lian-Hui Zhang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Single Molecule ◽  
Dominant Species ◽  
Bacterial Species ◽  
Secretion System ◽  
Interspecies Interactions ◽  
Type Vi Secretion System ◽  
Mixed Species ◽  
Type Vi Secretion ◽  
Biofilm Community

AbstractPseudomonas aeruginosais one of the dominant species when it co-exists with many other bacterial species in diverse environments. To understand its physiology and interactions with co-existing bacterial species in different conditions, we established physiologically reproducible eighteen-species communities, and found thatP. aeruginosabecame the dominant species in mixed-species biofilm community but not in the planktonic community.P. aeruginosaH1 type VI secretion system was highly induced in the mixed-species biofilm community compare to its mono-species biofilm, which was further demonstrated to play a key role forP. aeruginosato gain fitness over other bacterial species. In addition, the type IV pili and Psl exopolysaccharide were shown to be required forP. aeruginosato compete with other bacterial species in the biofilm community. Our study showed that the physiology ofP. aeruginosais strongly affected by interspecies interactions, and both biofilm determinants and H1 type VI secretion system contribute toP. aeruginosafitness over other species in complex biofilm communities.ImportancePseudomonas aeruginosausually coexists with different bacterial species in natural environment. However, systematic comparative characterization ofP. aeruginosain complex microbial communities with its mono-species communities is lacking. We constructed mixed-species planktonic and biofilm communities consistingP. aeruginosaand seventeen other bacterial species to study the physiology and interaction ofP. aeruginosain complex multiple-species community. A single molecule detection platform, NanoString nCounter®16S rRNA array, was used to shown thatP. aeruginosacan become the dominant species in the biofilm communities while not in the planktonic communities. Comparative transcriptomic analysis and fluorescence-based quantification further revealed thatP. aeruginosaH1 type VI secretion system and biofilm determinants are both required for its fitness in mixed-species biofilm communities.

scholarly journals Chelation of Membrane-Bound Cations by Extracellular DNA Activates the Type VI Secretion System in Pseudomonas aeruginosa

2016 ◽  
Vol 84 (8) ◽  
pp. 2355-2361 ◽  
Author(s):  
Mike Wilton ◽  
Megan J. Q. Wong ◽  
Le Tang ◽  
Xiaoye Liang ◽  
Richard Moore ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Adaptation Strategy ◽  
Secretion System ◽  
Extracellular Dna ◽  
Target Cells ◽  
Interspecies Interactions ◽  
Type Vi Secretion System ◽  
Content Type ◽  
Type Vi Secretion ◽  
Membrane Bound

Pseudomonas aeruginosaemploys its type VI secretion system (T6SS) as a highly effective and tightly regulated weapon to deliver toxic molecules to target cells. T6SS-secreted proteins ofP. aeruginosacan be detected in the sputum of cystic fibrosis (CF) patients, who typically present a chronic and polymicrobial lung infection. However, the mechanism of T6SS activation in the CF lung is not fully understood. Here we demonstrate that extracellular DNA (eDNA), abundant within the CF airways, stimulates the dynamics of the H1-T6SS cluster apparatus inPseudomonas aeruginosaPAO1. Addition of Mg2+or DNase with eDNA abolished such activation, while treatment with EDTA mimicked the eDNA effect, suggesting that the eDNA-mediated effect is due to chelation of outer membrane-bound cations. DNA-activated H1-T6SS enablesP. aeruginosato nonselectively attack neighboring species regardless of whether or not it was provoked. Because of the importance of the T6SS in interspecies interactions and the prevalence of eDNA in the environments thatP. aeruginosainhabits, our report reveals an important adaptation strategy that likely contributes to the competitive fitness ofP. aeruginosain polymicrobial communities.

Crystal Structure of the Type VI Secretion System Accessory Protein TagF from Pseudomonas Aeruginosa

2019 ◽  
Vol 26 (3) ◽  
pp. 204-214 ◽  
Author(s):  
Chang-Kyu Ok ◽  
Jeong Ho Chang
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Gene Cluster ◽  
Bacterial Species ◽  
Evolutionary Relationship ◽  
Secretion System ◽  
Transport Systems ◽  
Type Vi Secretion System ◽  
Related Molecule ◽  
Type Vi Secretion ◽  
Cloned Gene

Background: Type VI Secretion System (T6SS) has been found in approximately onequarter of the gram-negative bacterial species, and its structural characteristics appear to slightly differ from species to species. The genes encoding T6SS are designated as type six secretion A–M (tssA–M). The expression of the tss gene cluster is regulated by various accessory genes, designated as type VI-associated genes A–P (tagA–P). Tag family proteins have been commonly found in bacteria expressing T6SS but not in all bacterial species. For instance, the tag gene cluster is well-conserved in Pseudomonas aeruginosa (Pa). The PaTagF protein has large homology with ImpM in Rhizobium leguminosarum and SciT in Salmonella enterica. The overexpression of PaTagF represses T6SS complex accumulation and suppresses T6SS antibacterial activity. Thus, the functions of TagF are mediated through direct interactions with the forkhead-associated protein Fha, as evident from the results of the yeast-two hybrid assays. Fha is involved in recruiting a membrane-associated complex either in threonine phosphorylation pathway-dependent or - independent manner. However, functional reports of the tag gene cluster are still limited. </P><P> Objective: In this article, our motivation is to understand the molecular mechanism underlying the regulation of expression of the type VI secretion system complex. Methods: In this article, we start with obtaining the gene encoding PaTagF protein by polymerase chain reaction (PCR). Subsequently, the cloned gene is applied to overexpress of PaTagF protein in Escherichia coli, then purify the recombinant PaTagF protein. Thereafter, the protein is crystallized in a condition of 2.5 M NaCl, 0.1 M imidazole (pH 8.0), 3.2 M NaCl, 0.1 M BIS-TRIS propane (pH 7.0) and diffraction datasets of the PaTagF crystals are collected at the Pohang Accelerator Laboratory (PAL). The molecular structure of PaTagF protein is determined by molecular replacement using the uncharacterized protein PA0076 (PDB code:2QNU) as an initial search model by PHENIX crystallographic software package. Model building of PaTagF structure is performed using Coot program. Finally, the structural model is validated using phenix.refine program. Results: PaTagF exists as a tetramer in the asymmetric unit, and the overall fold of each monomer is composed of continuous beta-sheets wrapped by alpha-helices. Each monomer has variable conformations and lengths of both the N- and C-termini. Twelve residues, including the His6 tag from the N-terminus of a symmetry-related molecule, have been found in two of the tetrameric PaTagF structures. A structural homology search revealed that PaTagF was similar to the α-β-α sandwichlike structure of the longin domain on the differentially expressed in normal and neoplastic (DENN) superfamily, which is commonly found in proteins related to trafficking. Conclusion: The tetrameric structure of PaTagF comprises varied N- and C-terminal regions in each subunit and may be stabilized by a symmetry-related molecule. This feature was also shown in the TssL structure from V. cholerae. Furthermore, our study showed that the overall fold of PaTagF is homologous to the longin domain of the DENN family. Therefore, further studies are warranted to elucidate the structure-based evolutionary relationship between protein transport systems from the bacteria and eukaryotic cells.

scholarly journals T6SS Mediated Stress Responses for Bacterial Environmental Survival and Host Adaptation

2021 ◽  
Vol 22 (2) ◽  
pp. 478
Author(s):  
Kai-Wei Yu ◽  
Peng Xue ◽  
Yang Fu ◽  
Liang Yang
Keyword(s):  
Protein Secretion ◽  
Stress Responses ◽  
Current Knowledge ◽  
Bacterial Species ◽  
Host Cells ◽  
Interspecies Interactions ◽  
Type Vi Secretion System ◽  
Membrane Complex ◽  
Type Vi Secretion ◽  
Bacterial Type

The bacterial type VI secretion system (T6SS) is a protein secretion apparatus widely distributed in Gram-negative bacterial species. Many bacterial pathogens employ T6SS to compete with the host and to coordinate the invasion process. The T6SS apparatus consists of a membrane complex and an inner tail tube-like structure that is surrounded by a contractile sheath and capped with a spike complex. A series of antibacterial or antieukaryotic effectors is delivered by the puncturing device consisting of a Hcp tube decorated by the VgrG/PAAR complex into the target following the contraction of the TssB/C sheath, which often leads to damage and death of the competitor and/or host cells. As a tool for protein secretion and interspecies interactions, T6SS can be triggered by many different mechanisms to respond to various physiological conditions. This review summarizes our current knowledge of T6SS in coordinating bacterial stress responses against the unfavorable environmental and host conditions.

scholarly journals A New Front in Microbial Warfare—Delivery of Antifungal Effectors by the Type VI Secretion System

2019 ◽  
Vol 5 (2) ◽  
pp. 50 ◽  
Author(s):  
Katharina Trunk ◽  
Sarah J. Coulthurst ◽  
Janet Quinn
Keyword(s):  
Bacterial Species ◽  
Fungal Species ◽  
Secretion System ◽  
Effector Proteins ◽  
Primary Role ◽  
Bacterial Cells ◽  
Type Vi Secretion System ◽  
Type Vi Secretion ◽  
Bacteria And Fungi ◽  
Polymicrobial Communities

Microbes typically exist in mixed communities and display complex synergistic and antagonistic interactions. The Type VI secretion system (T6SS) is widespread in Gram-negative bacteria and represents a contractile nano-machine that can fire effector proteins directly into neighbouring cells. The primary role assigned to the T6SS is to function as a potent weapon during inter-bacterial competition, delivering antibacterial effectors into rival bacterial cells. However, it has recently emerged that the T6SS can also be used as a powerful weapon against fungal competitors, and the first fungal-specific T6SS effector proteins, Tfe1 and Tfe2, have been identified. These effectors act via distinct mechanisms against a variety of fungal species to cause cell death. Tfe1 intoxication triggers plasma membrane depolarisation, whilst Tfe2 disrupts nutrient uptake and induces autophagy. Based on the frequent coexistence of bacteria and fungi in microbial communities, we propose that T6SS-dependent antifungal activity is likely to be widespread and elicited by a suite of antifungal effectors. Supporting this hypothesis, homologues of Tfe1 and Tfe2 are found in other bacterial species, and a number of T6SS-elaborating species have been demonstrated to interact with fungi. Thus, we envisage that antifungal T6SS will shape many polymicrobial communities, including the human microbiota and disease-causing infections.

scholarly journals YbeY controls the type III and type VI secretion systems and biofilm formation through RetS in Pseudomonas aeruginosa

2020 ◽  
Author(s):  
Yushan Xia ◽  
Congjuan Xu ◽  
Dan Wang ◽  
Yuding Weng ◽  
Yongxin Jin ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Small Rnas ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Vi Secretion System ◽  
Chronic Infections ◽  
Type Iii ◽  
Type Vi Secretion

YbeY is a highly conserved RNase in bacteria and plays essential roles in the maturation of 16S rRNA, regulation of small RNAs (sRNAs) and bacterial responses to environmental stresses. Previously, we verified the role of YbeY in rRNA processing and ribosome maturation in Pseudomonas aeruginosa and demonstrated YbeY-mediated regulation of rpoS through a sRNA ReaL. In this study, we demonstrate that mutation of the ybeY gene results in upregulation of the type III secretion system (T3SS) genes as well as downregulation of the type VI secretion system (T6SS) genes and reduction of biofilm formation. By examining the expression of the known sRNAs in P. aeruginosa, we found that mutation of the ybeY gene leads to downregulation of the small RNAs RsmY/Z that control the T3SS, the T6SS and biofilm formation. Further studies revealed that the reduced levels of RsmY/Z are due to upregulation of retS. Taken together, our results reveal the pleiotropic functions of YbeY and provide detailed mechanisms of YbeY-mediated regulation in P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa causes a variety of acute and chronic infections in humans. The type III secretion system (T3SS) plays an important role in acute infection and the type VI secretion system (T6SS) and biofilm formation are associated with chronic infections. Understanding of the mechanisms that control the virulence determinants involved in acute and chronic infections will provide clues for the development of effective treatment strategies. Our results reveal a novel RNase mediated regulation on the T3SS, T6SS and biofilm formation in P. aeruginosa.

scholarly journals Type VI Secretion System Dynamics Reveals a Novel Secretion Mechanism in Pseudomonas aeruginosa

2018 ◽  
Vol 200 (11) ◽  
Author(s):  
Jacqueline Corbitt ◽  
Jun Seok Yeo ◽  
C. Ian Davis ◽  
Michele LeRoux ◽  
Paul A. Wiggins
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Vibrio Cholerae ◽  
Conformational Change ◽  
Secretion System ◽  
Force Generation ◽  
Type Vi Secretion System ◽  
Content Type ◽  
Evolutionary Diversification ◽  
Type Vi Secretion ◽  
Generation Mechanisms

ABSTRACT The type VI secretion system (T6SS) inhibits the growth of neighboring bacterial cells through a contact-mediated mechanism. Here, we describe a detailed characterization of the protein localization dynamics in the Pseudomonas aeruginosa T6SS. It has been proposed that the type VI secretion process is driven by a conformational-change-induced contraction of the T6SS sheath. However, although the contraction of an optically resolvable TssBC sheath and the subsequent localization of ClpV are observed in Vibrio cholerae , coordinated assembly and disassembly of TssB and ClpV are observed without TssB contraction in P. aeruginosa . These dynamics are inconsistent with the proposed contraction sheath model. Motivated by the phenomenon of dynamic instability, we propose a new model in which ATP hydrolysis, rather than conformational change, generates the force for secretion. IMPORTANCE The type VI secretion system (T6SS) is widely conserved among Gram-negative bacteria and is a central determinant of bacterial fitness in polymicrobial communities. The secretion system targets bacteria and secretes effectors that inhibit the growth of neighboring cells, using a contact-mediated-delivery system. Despite significant homology to the previously characterized Vibrio cholerae T6SS, our analysis reveals that effector secretion is driven by a distinct force generation mechanism in Pseudomonas aeruginosa . The presence of two distinct force generation mechanisms in T6SS represents an example of the evolutionary diversification of force generation mechanisms.

scholarly journals Host Adaptation Predisposes Pseudomonas aeruginosa to Type VI Secretion System-Mediated Predation by the Burkholderia cepacia Complex

2020 ◽  
Vol 28 (4) ◽  
pp. 534-547.e3 ◽  
Author(s):  
Andrew I. Perault ◽  
Courtney E. Chandler ◽  
David A. Rasko ◽  
Robert K. Ernst ◽  
Matthew C. Wolfgang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Burkholderia Cepacia ◽  
Host Adaptation ◽  
Secretion System ◽  
Burkholderia Cepacia Complex ◽  
Type Vi Secretion System ◽  
Type Vi Secretion

scholarly journals A Type VI Secretion System of Pseudomonas aeruginosa Targets a Toxin to Bacteria

2010 ◽  
Vol 7 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Rachel D. Hood ◽  
Pragya Singh ◽  
FoSheng Hsu ◽  
Tüzün Güvener ◽  
Mike A. Carl ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Secretion System ◽  
Type Vi Secretion System ◽  
Type Vi Secretion
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