Type B CTD Proteins Secreted by the Type IX Secretion System Associate with PorP-like Proteins for Cell Surface Anchorage.

The type IX secretion system (T9SS) consists of at least 20 components that translocate proteins with type A or type B C-terminal domain (CTD) signals across the outer membrane (OM). While type A CTD proteins are anchored to the cell surface via covalent linkage to the anionic lipopolysaccharide, it is still unclear how type B CTD proteins are anchored to the cell surface. Moreover, very little is known about the PorE and PorP components of the T9SS.

Complementation in of Porphyromonas gingivalis Lipopolysaccharide Biosynthetic Mutants Demonstrates Lipopolysaccharide Exchange.

, a bacterial pathogen contributing to human periodontitis, exports and anchors cargo proteins to its surface, enabling the production of black pigmentation using a type IX secretion system (T9SS) and conjugation to anionic lipopolysaccharide (A-LPS). To determine whether T9SS components need to be assembled for correct secretion and A-LPS modification of cargo proteins, combinations of nonpigmented mutants lacking A-LPS or a T9SS component were mixed to investigate in complementation. Reacquisition of pigmentation occurred only between an A-LPS mutant and a T9SS mutant, which coincided with A-LPS modification of cargo proteins detected by Western blotting and coimmunoprecipitation/quantitative mass spectrometry.

Type IX Secretion System Cargo Proteins Are Glycosylated at the C Terminus with a Novel Linking Sugar of the Wbp/Vim Pathway.

and use the type IX secretion system to secrete cargo proteins to the cell surface where they are anchored via glycolipids. In , the glycolipid is anionic lipopolysaccharide (A-LPS), of partially known structure. Modified cargo proteins were deglycosylated using trifluoromethanesulfonic acid and digested with trypsin or proteinase K.

Quantitative proteomic analysis of the type IX secretion system mutants in Porphyromonas gingivalis.

Porphyromonas gingivalis is an anaerobic, gram-negative human oral pathogen highly associated with chronic periodontitis. P. gingivalis utilizes the type IX secretion system (T9SS) to transport many of its virulence factors including the gingipains to the cell surface.

Localization of Outer Membrane Proteins in Treponema denticola by Quantitative Proteome Analyses of Outer Membrane Vesicles and Cellular Fractions.

The identification and localization of outer membrane proteins (Omps) and lipoproteins in pathogenic treponemes such as T. denticola (periodontitis) and T. pallidum (syphilis) has been challenging.

PorV is an Outer Membrane Shuttle Protein for the Type IX Secretion System.

Porphyromonas gingivalis is a keystone pathogen associated with chronic periodontitis. Major virulence factors named gingipains (cysteine proteinases, RgpA, RgpB and Kgp) are secreted via the Type IX Secretion System (T9SS). These, together with approximately 30 other proteins, are secreted to the cell surface and anchored to the outer membrane by covalent modification to anionic lipopolysaccharide (A-LPS) via the novel Gram negative sortase, PorU.

Type IX secretion: the generation of bacterial cell surface coatings involved in virulence, gliding motility and the degradation of complex biopolymers.

The Type IX secretion system (T9SS) is present in over 1000 sequenced species/strains of the Fibrobacteres-Chlorobi-Bacteroidetes superphylum. Proteins secreted by the T9SS have an N-terminal signal peptide for translocation across the inner membrane via the SEC translocon and a C-terminal signal for secretion across the outer membrane via the T9SS. Nineteen protein components of the T9SS have been identified including three, SigP, PorX and PorY that are involved in regulation.

Structural Insights into the PorK and PorN Components of the Porphyromonas gingivalis Type IX Secretion System.

The type IX secretion system (T9SS) has been recently discovered and is specific to Bacteroidetes species. Porphyromonas gingivalis, a keystone pathogen for periodontitis, utilizes the T9SS to transport many proteins including the gingipain virulence factors across the outer membrane and attach them to the cell surface via a sortase-like mechanism. At least 11 proteins have been identified as components of the T9SS including PorK, PorL, PorM, PorN and PorP, however the precise roles of most of these proteins have not been elucidated and the structural organization of these components is unknown.

Porphyromonas gingivalis Type IX Secretion Substrates Are Cleaved and Modified by a Sortase-Like Mechanism.

The type IX secretion system (T9SS) of Porphyromonas gingivalis secretes proteins possessing a conserved C-terminal domain (CTD) to the cell surface. The C-terminal signal is essential for these proteins to translocate across the outer membrane via the T9SS. On the surface the CTD of these proteins is cleaved prior to extensive glycosylation.

The Porphyromonas gingivalis ferric uptake regulator orthologue binds hemin and regulates hemin-responsive biofilm development.

Porphyromonas gingivalis is a Gram-negative pathogen associated with the biofilm-mediated disease chronic periodontitis. P. gingivalis biofilm formation is dependent on environmental heme for which P.

Blue native-PAGE analysis of membrane protein complexes in Porphyromonas gingivalis.

Unlabelled: Membrane complexes of Porphyromonas gingivalis were analyzed using two dimensional-blue native-PAGE. The molecular mass of the gingipain complexes, RgpA and Kgp, ranged from 450 kDa to greater than 1200 kDa, and did not change in single rgpA and kgp mutants indicating that the proteolytically processed polyproteins were independently capable of forming complexes. The outer membrane protein, LptO, which is essential for gingipain secretion, was found in up to seven different complex sizes.

Porphyromonas gingivalis outer membrane vesicles exclusively contain outer membrane and periplasmic proteins and carry a cargo enriched with virulence factors.

Porphyromonas gingivalis, a keystone pathogen associated with chronic periodontitis, produces outer membrane vesicles (OMVs) that carry a cargo of virulence factors. In this study, the proteome of OMVs was determined by LC-MS/MS analyses of SDS-PAGE fractions, and a total of 151 OMV proteins were identified, with all but one likely to have originated from either the outer membrane or periplasm. Of these, 30 exhibited a C-terminal secretion signal known as the CTD that localizes them to the cell/vesicle surface, 79 and 27 were localized to the vesicle membrane and lumen respectively while 15 were of uncertain location.

A novel transposon construct expressing PhoA with potential for studying protein expression and translocation in Mycoplasma gallisepticum.

Background: Mycoplasma gallisepticum is a major poultry pathogen and causes severe economic loss to the poultry industry. In mycoplasmas lipoproteins are abundant on the membrane surface and play a critical role in interactions with the host, but tools for exploring their molecular biology are limited.

Results: In this study we examined whether the alkaline phosphatase gene (phoA ) from Escherichia coli could be used as a reporter in mycoplasmas.

PG0026 is the C-terminal signal peptidase of a novel secretion system of Porphyromonas gingivalis.

Protein substrates of a novel secretion system of Porphyromonas gingivalis contain a conserved C-terminal domain (CTD) of ∼70-80 amino acid residues that is essential for their secretion and attachment to the cell surface. The CTD itself has not been detected in mature substrates, suggesting that it may be removed by a novel signal peptidase. More than 10 proteins have been shown to be essential for the proper functioning of the secretion system, and one of these, PG0026, is a predicted cysteine proteinase that also contains a CTD, suggesting that it may be a secreted component of the secretion system and a candidate for being the CTD signal peptidase.

Molecular typing of Mycoplasma agalactiae: tracing European-wide genetic diversity and an endemic clonal population.

Mycoplasma agalactiae causes chronic infections in small ruminants and remains endemic in many regions of the world, despite intensive and costly eradication programs. In this study, the innate genomic plasticity of M. agalactiae was exploited to design and assess a combination of molecular epidemiological tools to trace the pathogen in different geographic locations and to understand its emergence or re-emergence after eradication campaigns.

The outer membrane protein LptO is essential for the O-deacylation of LPS and the co-ordinated secretion and attachment of A-LPS and CTD proteins in Porphyromonas gingivalis.

Protein substrates of a novel secretion system of Porphyromonas gingivalis contain a conserved C-terminal domain (CTD) essential for secretion and attachment to the cell surface. Inactivation of lptO (PG0027) or porT produced mutants that lacked surface protease activity and an electron-dense surface layer. Both mutants showed co-accumulation of A-LPS and unmodified CTD proteins in the periplasm.

Experimental evolution of a plant pathogen into a legume symbiont.

Rhizobia are phylogenetically disparate alpha- and beta-proteobacteria that have achieved the environmentally essential function of fixing atmospheric nitrogen in symbiosis with legumes. Ample evidence indicates that horizontal transfer of symbiotic plasmids/islands has played a crucial role in rhizobia evolution. However, adaptive mechanisms that allow the recipient genomes to express symbiotic traits are unknown.

Occurrence, plasticity, and evolution of the vpma gene family, a genetic system devoted to high-frequency surface variation in Mycoplasma agalactiae.

Mycoplasma agalactiae, an important pathogen of small ruminants, exhibits a very versatile surface architecture by switching multiple, related lipoproteins (Vpmas) on and off. In the type strain, PG2, Vpma phase variation is generated by a cluster of six vpma genes that undergo frequent DNA rearrangements via site-specific recombination. To further comprehend the degree of diversity that can be generated at the M.

Genome sequence of the beta-rhizobium Cupriavidus taiwanensis and comparative genomics of rhizobia.

We report the first complete genome sequence of a beta-proteobacterial nitrogen-fixing symbiont of legumes, Cupriavidus taiwanensis LMG19424. The genome consists of two chromosomes of size 3.42 Mb and 2.

Phase-locked mutants of Mycoplasma agalactiae: defining the molecular switch of high-frequency Vpma antigenic variation.

Mycoplasma agalactiae, an important pathogen of small ruminants, exhibits antigenic diversity by switching the expression of multiple surface lipoproteins called Vpmas (Variable proteins of M. agalactiae). Although phase variation has been shown to play important roles in many host-pathogen interactions, the biological significance and the mechanism of Vpma oscillations remain largely unclear.

[Molecular basis of Mycoplasma agalactiae pathogenicity].

Compared to other bacterial pathogens, the current knowledge of the molecular basis of pathogenicity of mycoplasmas is limited, and their strategies of infection at the molecular and cellular level remain to be elucidated. Several studies in the past years have shown that pathogenic mycoplasmas are equipped with sophisticated genetic systems, which allow these agents to spontaneously change their surface antigenic make-up. It is implicated that these variable surface components provide the wall-less mycoplasmas with a means to avoid the host immune response and promote host colonization.

Surface diversity in Mycoplasma agalactiae is driven by site-specific DNA inversions within the vpma multigene locus.

The ruminant pathogen Mycoplasma agalactiae possesses a family of abundantly expressed variable surface lipoproteins called Vpmas. Phenotypic switches between Vpma members have previously been correlated with DNA rearrangements within a locus of vpma genes and are proposed to play an important role in disease pathogenesis. In this study, six vpma genes were characterized in the M.

A gene family in Mycoplasma imitans closely related to the pMGA family of Mycoplasma gallisepticum.

The avian pathogen Mycoplasma gallisepticum possesses a large gene family encoding lipoproteins which function as haemagglutinins. Representative species of the pneumoniae phylogenetic group of mycoplasmas were examined for the presence of genes homologous to members of this multigene family. Antisera against the pMGA1.

Size and genomic location of the pMGA multigene family of Mycoplasma gallisepticum.

The pMGA multigene family encodes variant copies of the cell surface haemagglutinin of Mycoplasma gallisepticum. Quantitative Southern blotting, using an oligonucleotide probe complementary to a region conserved in the leader sequence of all known pMGA genes, was used to estimate the number of members of the family in the genome of seven strains of M. gallisepticum.