Secretion and subcellular localizations of bacterial proteins: a semantic awareness issue

Desvaux, Mickaël; Hébraud, Michel; Talon, Régine; Henderson, Ian R.

doi:10.1016/j.tim.2009.01.004

Cited by 316 publications

(285 citation statements)

References 46 publications

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“…Outer membrane proteins with conserved antigenic Pfam domains (PF07244 and PF01103) are also often found in diderm bacteria , but the encoding genes were also absent in the Cfx-K genome. The same conclusion was reached for all examined outer membrane transporter genes, including those associated with the secretin-based type II and III secretion systems (Supplementary Figure S3; Desvaux et al, 2009). Genes encoding membrane-associated proteins with Pfam domains, commonly seen in monoderm bacteria (PF02645, PF03816, PF09269 and PF01424; Albertsen et al, 2013), could all be identified in the Cfx-K genome (Supplementary Figure S3).…”

Section: Surface Properties Of the B45 Phylotypesupporting

confidence: 62%

Genomic and in situ investigations of the novel uncultured Chloroflexi associated with 0092 morphotype filamentous bulking in activated sludge

et al. 2016

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Overgrowth of filamentous bacteria in activated sludge wastewater treatment plants (WWTPs) leads to impaired sludge settleability, a condition known as bulking, which is a common operational problem worldwide. Filaments with the Eikelboom 0092 morphotype are commonly associated with such bulking episodes. Members of the uncultured B45 phylotype, which is embraced within the phylum Chloroflexi, were recently shown to exhibit this morphology. Although these organisms are among the most abundant populations recorded in activated sludge processes, nothing is known about their metabolic characteristics. In this study, a genome sequence, representing the B45 phylotype, was retrieved from a metagenome generated from an activated sludge WWTP. The genome consisted of two chromosomes and one plasmid, which were 4.0, 1.0 and 0.04 Mbps in size, respectively. A metabolic model was constructed for this organism, based on annotation of its genome, showing its ability to generate energy by respiration, utilizing oxygen, nitrite or nitrous oxide as electron acceptors, or by fermentation of sugars. The ability of B45 members to ferment sugars under anaerobic conditions was validated in situ with microautoradiography-fluorescence in situ hybridization. The provisional name of 'Candidatus Promineofilum breve' is proposed for this species. This study represents the first detailed information on an uncultured genus of filamentous organisms from activated sludge.

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Section: Surface Properties Of the B45 Phylotypesupporting

confidence: 62%

Genomic and in situ investigations of the novel uncultured Chloroflexi associated with 0092 morphotype filamentous bulking in activated sludge

et al. 2016

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“…The formation of the curli, however, is a surprisingly complex process being produced via the extracellular nucleation-precipitation pathway or the type VIII secretion system (22). Seven products (CsgA, CsgB, CsgC, CsgD, CsgE, CsgF, and CsgG) of two operons (csgBAC and csgDEFG) cooperate to facilitate curli fiber formation (2,23,24).…”

mentioning

confidence: 99%

Solution NMR structure of CsgE: Structural insights into a chaperone and regulator protein important for functional amyloid formation

Krezel

Cusumano

Pinkner

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Curli, consisting primarily of major structural subunit CsgA, are functional amyloids produced on the surface of Escherichia coli, as well as many other enteric bacteria, and are involved in cell colonization and biofilm formation. CsgE is a periplasmic accessory protein that plays a crucial role in curli biogenesis. CsgE binds to both CsgA and the nonameric pore protein CsgG. The CsgG-CsgE complex is the curli secretion channel and is essential for the formation of the curli fibril in vivo. To better understand the role of CsgE in curli formation, we have determined the solution NMR structure of a double mutant of CsgE (W48A/F79A) that appears to be similar to the wild-type (WT) protein in overall structure and function but does not form mixed oligomers at NMR concentrations similar to the WT. The well-converged structure of this mutant has a core scaffold composed of a layer of two α-helices and a layer of three-stranded antiparallel β-sheet with flexible N and C termini. The structure of CsgE fits well into the cryoelectron microscopy density map of the CsgG-CsgE complex. We highlight a striking feature of the electrostatic potential surface in CsgE structure and present an assembly model of the CsgG-CsgE complex. We suggest a structural mechanism of the interaction between CsgE and CsgA. Understanding curli formation can provide the information necessary to develop treatments and therapeutic agents for biofilm-related infections and may benefit the prevention and treatment of amyloid diseases. CsgE could establish a paradigm for the regulation of amyloidogenesis because of its unique role in curli formation.biofilm formation | intrinsically disordered protein | aggregation | protein-protein interaction | CsgG

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“…The curli biogenesis pathway is often termed type VIII secretion system, or nucleation-precipitation secretion pathway, because the fiber growth is dependent on the presence of a nucleator molecule (3,9). In Escherichia coli, this system is composed of the products of seven curli-specific genes (csg) encoded by two separately transcribed operons, csgBAC and csgDEFG (10).…”

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confidence: 99%

Structure of the nonameric bacterial amyloid secretion channel

Cao

Zhao

Kou

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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102

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Various strains of bacteria are able to produce a unique class of functional amyloids termed curli, which are critical for biofilm formation, host cell adhesion, and colonization of inert surfaces. Curli are secreted via the type VIII bacterial secretion system, and they share biochemical and structural characteristics with amyloid fibers that have been implicated in deleterious disease in humans. Here, we report the crystal structure of Escherichia coli CsgG, which is an essential lipoprotein component of the type VIII secretion system and which forms a secretion channel in the bacterial outer membrane for transporting curli subunits. CsgG forms a crown-shaped, symmetric nonameric channel that spans the outer membrane via a 36-strand β-barrel, with each subunit contributing four β-strands. This nonameric complex contains a central channel with a pore located at the middle. The eyelet of the pore is ∼12 Å in diameter and is lined with three stacked nine-residue rings consisting of Tyr-66, Asn-70, or Phe-71. Our structure-based functional studies suggest that Tyr-66 and Phe-71 residues function as gatekeepers for the selective secretion of curli subunits. Our study describes in detail, to our knowledge, the first core structure of the type VIII bacterial secretion machinery. Importantly, our structural analysis suggests that the curli subunits are secreted via CsgG across the bacterial outer membrane in an unfolded form.CsgG | curli | amyloids | outer membrane protein | biofilm

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Secretion and subcellular localizations of bacterial proteins: a semantic awareness issue

Cited by 316 publications

References 46 publications

Genomic and in situ investigations of the novel uncultured Chloroflexi associated with 0092 morphotype filamentous bulking in activated sludge

Genomic and in situ investigations of the novel uncultured Chloroflexi associated with 0092 morphotype filamentous bulking in activated sludge

Solution NMR structure of CsgE: Structural insights into a chaperone and regulator protein important for functional amyloid formation

Structure of the nonameric bacterial amyloid secretion channel

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