scholarly journals Analysis of ATPases of putative secretion operons in the thermoacidophilic archaeon Sulfolobus solfataricus

Microbiology ◽  
2005 ◽  
Vol 151 (3) ◽  
pp. 763-773 ◽  
Author(s):  
Sonja-Verena Albers ◽  
Arnold J. M. Driessen
Keyword(s):  
Expression Patterns ◽  
Sulfolobus Solfataricus ◽  
Gene Clusters ◽  
Growth Conditions ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Gram Negative ◽  
Type Iv ◽  
Encoding Gene ◽  
Bacterial Secretion

Gram-negative bacteria use a wide variety of complex mechanisms to secrete proteins across their membranes or to assemble secreted proteins into surface structures. As most archaea only possess a cytoplasmic membrane surrounded by a membrane-anchored S-layer, the organization of such complexes might be significantly different from that in Gram-negative bacteria. Five proteins of Sulfolobus solfataricus, SSO0120, SSO0572, SSO2316, SSO2387 and SSO2680, which are homologous to secretion ATPases of bacterial type II, type IV secretion systems and the type IV pili assembly machinery, were identified. The operon structures of these putative secretion systems encoding gene clusters and the expression patterns of the ATPases under different growth conditions were determined, and it was established that all five putative ATPases do show a divalent cation-dependent ATPase activity at high temperature. These results show that the archaeal secretion systems are related to the bacterial secretion systems and might be powered in a similar way.

scholarly journals Bactericidal Type IV Secretion System Homeostasis in Xanthomonas citri

2019 ◽  
Author(s):  
William Cenens ◽  
Maxuel O. Andrade ◽  
Chuck S. Farah
Keyword(s):  
Cell Envelope ◽  
Growth Conditions ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Gram Negative Bacteria ◽  
Global Regulator ◽  
Xanthomonas Citri ◽  
Gram Negative ◽  
Type Iv

AbstractSeveral Xanthomonas species have a type IV secretion system (T4SS) that injects a cocktail of antibacterial proteins into neighbouring Gram-negative bacteria, often leading to rapid lysis upon cell contact. This capability represents an obvious fitness benefit since it can eliminate competition while the liberated contents of the lysed bacteria could provide an increase in the local availability of nutrients. However, the production of this Mega Dalton-sized T4SS, with over a hundred subunits, also imposes a significant metabolic cost. Here we show that the chromosomal virB operon, which encodes the entirety of structural genes of the T4SS in X. citri, is regulated by the global regulator CsrA. Relieving CsrA repression from the virB operon produced a greater number of T4SSs in the cell envelope and an increased efficiency in contact dependent lysis of target cells. However, this was also accompanied by a physiological cost leading to reduced fitness when in co-culture with wild-type X. citri. We show that T4SS production is constitutive despite being downregulated by CsrA. Cells subjected to a wide range of rich and poor growth conditions maintain a constant density of T4SSs in the cell envelope and concomitant interbacterial competitiveness. These results show that CsrA provides a constant though partial repression on the virB operon, independent of the tested growth conditions, in this way controlling T4SS-related costs while at the same time maintaining X. citri’s aggressive posture when confronted by competitors.Author SummaryXanthomonas citri is a member of a family of phytopathogenic bacteria that can cause substantial losses in crops. At different stages of the infection cycle, these cells will encounter other bacterial species with whom they will have to compete for space and nutrients. One mechanism which improves a cell’s chance to survive these encounters is a type IV secretion system that transfers a cocktail of antimicrobial effector proteins into other Gram-negative bacteria in a contact-dependent manner. Here, we show that this system is constitutively produced at a low basal level, even during low nutrient conditions, despite representing a significant metabolic burden to the cell. The conserved global regulator, CsrA, provides a constant, nutrient-independent, repression on the production T4SS components, thereby holding production costs to a minimum while at the same time ensuring X. citri’s competitiveness during encounters with bacterial rivals.

Two-step and one-step secretion mechanisms in Gram-negative bacteria: contrasting the type IV secretion system and the chaperone-usher pathway of pilus biogenesis

2010 ◽  
Vol 425 (3) ◽  
pp. 475-488 ◽  
Author(s):  
Ana Toste Rêgo ◽  
Vidya Chandran ◽  
Gabriel Waksman
Keyword(s):  
Pathogenic Bacteria ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Extracellular Medium ◽  
Gram Negative ◽  
Type Iv ◽  
Pilus Biogenesis ◽  
One Step ◽  
Step Mechanism

Gram-negative bacteria have evolved diverse secretion systems/machineries to translocate substrates across the cell envelope. These various machineries fulfil a wide variety of functions but are also essential for pathogenic bacteria to infect human or plant cells. Secretion systems, of which there are seven, utilize one of two secretion mechanisms: (i) the one-step mechanism, whereby substrates are translocated directly from the bacterial cytoplasm to the extracellular medium or into the eukaryotic target cell; (ii) the two-step mechanism, whereby substrates are first translocated across the bacterial inner membrane; once in the periplasm, substrates are targeted to one of the secretion systems that mediate transport across the outer membrane and released outside the bacterial cell. The present review provides an example for each of these two classes of secretion systems and contrasts the various solutions evolved to secrete substrates.

scholarly journals Clonal Clusters, Molecular Resistance Mechanisms and Virulence Factors of Gram-Negative Bacteria Isolated from Chronic Wounds in Ghana

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 339
Author(s):  
Denise Dekker ◽  
Frederik Pankok ◽  
Thorsten Thye ◽  
Stefan Taudien ◽  
Kwabena Oppong ◽  
...  
Keyword(s):  
Molecular Epidemiology ◽  
Virulence Factors ◽  
Iron Uptake ◽  
Chronic Wounds ◽  
Sub Saharan Africa ◽  
Gram Negative Bacteria ◽  
Beta Lactamase ◽  
Secretion Systems ◽  
Gram Negative ◽  
E Coli

Wound infections are common medical problems in sub-Saharan Africa but data on the molecular epidemiology are rare. Within this study we assessed the clonal lineages, resistance genes and virulence factors of Gram-negative bacteria isolated from Ghanaian patients with chronic wounds. From a previous study, 49 Pseudomonas aeruginosa, 21 Klebsiellapneumoniae complex members and 12 Escherichia coli were subjected to whole genome sequencing. Sequence analysis indicated high clonal diversity with only nine P. aeruginosa clusters comprising two strains each and one E. coli cluster comprising three strains with high phylogenetic relationship suggesting nosocomial transmission. Acquired beta-lactamase genes were observed in some isolates next to a broad spectrum of additional genetic resistance determinants. Phenotypical expression of extended-spectrum beta-lactamase activity in the Enterobacterales was associated with blaCTX-M-15 genes, which are frequent in Ghana. Frequently recorded virulence genes comprised genes related to invasion and iron-uptake in E. coli, genes related to adherence, iron-uptake, secretion systems and antiphagocytosis in P. aeruginosa and genes related to adherence, biofilm formation, immune evasion, iron-uptake and secretion systems in K. pneumonia complex. In summary, the study provides a piece in the puzzle of the molecular epidemiology of Gram-negative bacteria in chronic wounds in rural Ghana.

scholarly journals Folding Control in the Path of Type 5 Secretion

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 341
Author(s):  
Nathalie Dautin
Keyword(s):  
Protein Folding ◽  
Virulence Factors ◽  
Secretion System ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Gram Negative ◽  
Final Destination ◽  
Cell Compartments ◽  
Recent Addition ◽  
Functionally Diverse

The type 5 secretion system (T5SS) is one of the more widespread secretion systems in Gram-negative bacteria. Proteins secreted by the T5SS are functionally diverse (toxins, adhesins, enzymes) and include numerous virulence factors. Mechanistically, the T5SS has long been considered the simplest of secretion systems, due to the paucity of proteins required for its functioning. Still, despite more than two decades of study, the exact process by which T5SS substrates attain their final destination and correct conformation is not totally deciphered. Moreover, the recent addition of new sub-families to the T5SS raises additional questions about this secretion mechanism. Central to the understanding of type 5 secretion is the question of protein folding, which needs to be carefully controlled in each of the bacterial cell compartments these proteins cross. Here, the biogenesis of proteins secreted by the Type 5 secretion system is discussed, with a focus on the various factors preventing or promoting protein folding during biogenesis.

scholarly journals BastionHub: a universal platform for integrating and analyzing substrates secreted by Gram-negative bacteria

2020 ◽  
Vol 49 (D1) ◽  
pp. D651-D659
Author(s):  
Jiawei Wang ◽  
Jiahui Li ◽  
Yi Hou ◽  
Wei Dai ◽  
Ruopeng Xie ◽  
...  
Keyword(s):  
Rapid Development ◽  
Single Type ◽  
Computational Techniques ◽  
Type I ◽  
Gram Negative Bacteria ◽  
Bacterial Survival ◽  
Secretion Systems ◽  
Gram Negative ◽  
Relationship Analysis ◽  
Depth Analysis

Abstract Gram-negative bacteria utilize secretion systems to export substrates into their surrounding environment or directly into neighboring cells. These substrates are proteins that function to promote bacterial survival: by facilitating nutrient collection, disabling competitor species or, for pathogens, to disable host defenses. Following a rapid development of computational techniques, a growing number of substrates have been discovered and subsequently validated by wet lab experiments. To date, several online databases have been developed to catalogue these substrates but they have limited user options for in-depth analysis, and typically focus on a single type of secreted substrate. We therefore developed a universal platform, BastionHub, that incorporates extensive functional modules to facilitate substrate analysis and integrates the five major Gram-negative secreted substrate types (i.e. from types I–IV and VI secretion systems). To our knowledge, BastionHub is not only the most comprehensive online database available, it is also the first to incorporate substrates secreted by type I or type II secretion systems. By providing the most up-to-date details of secreted substrates and state-of-the-art prediction and visualized relationship analysis tools, BastionHub will be an important platform that can assist biologists in uncovering novel substrates and formulating new hypotheses. BastionHub is freely available at http://bastionhub.erc.monash.edu/.

scholarly journals Chaperone–usher pathways: diversity and pilus assembly mechanism

2012 ◽  
Vol 367 (1592) ◽  
pp. 1112-1122 ◽  
Author(s):  
Andreas Busch ◽  
Gabriel Waksman
Keyword(s):  
Bacterial Pathogens ◽  
Surface Structures ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Gram Negative ◽  
Assembly Mechanism ◽  
Adhesive Surface ◽  
Different Types ◽  
Pilus Assembly

Up to eight different types of secretion systems, and several more subtypes, have been described in Gram-negative bacteria. Here, we focus on the diversity and assembly mechanism of one of the best-studied secretion systems, the widespread chaperone–usher pathway known to assemble and secrete adhesive surface structures, called pili or fimbriae, which play essential roles in targeting bacterial pathogens to the host.

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