Protein Circlets as Sex Pilus Subunits

Kalkum, Markus; Eisenbrandt, Ralf; Lanka, Erich

doi:10.2174/1389203043379639

Cited by 21 publications

(19 citation statements)

References 43 publications

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“…The signal sequences of these proteins are processed in the IM, with subsequent species-specific processing of the C and/or N termini (44,45,72,78,80,92,112). This role in T-pilus formation is supported by findings from various studies demon-FIG.…”

Section: The Enigmatic Rvhb2 Proteinsmentioning

confidence: 76%

Phylogenomics Reveals a DiverseRickettsialesType IV Secretion System

et al. 2010

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3With an obligate intracellular lifestyle, Alphaproteobacteria of the order Rickettsiales have inextricably coevolved with their various eukaryotic hosts, resulting in small, reductive genomes and strict dependency on host resources. Unsurprisingly, large portions of Rickettsiales genomes encode proteins involved in transport and secretion. One particular transporter that has garnered recent attention from researchers is the type IV secretion system (T4SS). Homologous to the well-studied archetypal vir T4SS of Agrobacterium tumefaciens, the Rickettsiales vir homolog (rvh) T4SS is characterized primarily by duplication of several of its genes and scattered genomic distribution of all components in several conserved islets. Phylogeny estimation suggests a single event of ancestral acquirement of the rvh T4SS, likely from a nonalphaproteobacterial origin. Bioinformatics analysis of over 30 Rickettsiales genome sequences illustrates a conserved core rvh scaffold (lacking only a virB5 homolog), with lineage-specific diversification of several components (rvhB1, rvhB2, and rvhB9b), likely a result of modifications to cell envelope structure. This coevolution of the rvh T4SS and cell envelope morphology is probably driven by adaptations to various host cells, identifying the transporter as an important target for vaccine development. Despite the genetic intractability of Rickettsiales, recent advancements have been made in the characterization of several components of the rvh T4SS, as well as its putative regulators and substrates. While current data favor a role in effector translocation, functions in DNA uptake and release and/or conjugation cannot at present be ruled out, especially considering that a mechanism for plasmid transfer in Rickettsia spp. has yet to be proposed.Type IV secretion systems (T4SSs) are macromolecular complexes that transport protein, DNA, and nucleoprotein across the bacterial cell envelope in both Gram-negative and Gram-positive species, as well as some wall-less bacteria and archaea (1, 32). Functioning in naked DNA uptake and release (60), conjugation (80), and the propagation of genomic islands (69), T4SSs are prominent factors in bacterial diversification and are responsible for the horizontal spread of antimicrobial resistance and virulence genes. T4SSs are also used by some species to deliver effector molecules (DNA and/or protein) into eukaryotic host cells (28), a process that facilitates infection and subsequent pathogenesis. It is assumed that all varieties of T4SSs form a channel that spans the cell envelope and culminates in a surface-exposed structure, such as a pilus (Fig. 1A). Despite this conserved architecture, genetic diversity in a multitude of features, including gene composition and organization, underlies the hundreds of T4SSs identified through genome sequencing. Recently, T4SSs have been classified into four groups: F, P, I, and GI (70). F-T4SSs and P-T4SSs (previously known as type IVA) are widespread systems represented by the archetypes encoded by the F plasmid o...

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Section: The Enigmatic Rvhb2 Proteinsmentioning

confidence: 76%

Phylogenomics Reveals a DiverseRickettsialesType IV Secretion System

et al. 2010

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“…VirB2 (121 residues) is the major pilin subunit of the A. tumefaciens VirB/VirD4 T-pilus and an essential component of the secretion channel (40,41). The VirB2 pilin is processed by cleavage of an unusually long leader peptide (47 amino acids) to produce the T-pilin, whereas the TrbC pilin (145 residues) undergoes multiple processing for maturation (see below).…”

Section: Prokaryotic Circular Proteinsmentioning

confidence: 99%

“…The T-pilus is composed of T-pilin and VirB5 subunits (39,40). The resulting pilins are assembled into flexuous filaments projecting from the bacterial cell wall via expression of a large set of genes (41). T-pili are generated when A. tumefaciens cells are naturally induced by plant phenolic compounds or induced in vitro, which leads to the expression of the virB operon (11 genes) located on the resident Ti plasmid (39).…”

Section: Prokaryotic Circular Proteinsmentioning

confidence: 99%

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Discovering the Bacterial Circular Proteins: Bacteriocins, Cyanobactins, and Pilins

Montalbán-López

Sánchez‐Hidalgo

Cebrián

et al. 2012

Journal of Biological Chemistry

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“…Recently, the structure of the F pilus was determined using cryo-EM and single-particle reconstruction (18). In contrast to the pilin subunits of F-type pili, P-type pili undergo maturation steps leading to the formation of a cyclic protein (19).…”

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confidence: 99%

Processing and Maturation of the Pilin of the Type IV Secretion System Encoded within the Gonococcal Genetic Island

Jain

Kahnt

Does

2011

Journal of Biological Chemistry

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Background: Circularization of a pilin of a type IV secretion system. Results: The TraA pilin encoded within the gonoccocal genetic island is circularized by the signal peptidase LepB and the TrbI peptidase. Conclusion:The circularization reaction shows limited flexibility in the length of the N and C termini and occurs via a covalent intermediate. Significance: This is the first demonstration of a covalent intermediate in pilin circularization.

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Protein Circlets as Sex Pilus Subunits

Cited by 21 publications

References 43 publications

Phylogenomics Reveals a DiverseRickettsialesType IV Secretion System

Phylogenomics Reveals a DiverseRickettsialesType IV Secretion System

Discovering the Bacterial Circular Proteins: Bacteriocins, Cyanobactins, and Pilins

Processing and Maturation of the Pilin of the Type IV Secretion System Encoded within the Gonococcal Genetic Island

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