Cell-cell interactions in conjugating Escherichia coli: role of F pili and fate of mating aggregates

Achtman, Mark; Morelli, Giovanna; Schwuchow, S

doi:10.1128/jb.135.3.1053-1061.1978

Cited by 95 publications

(30 citation statements)

References 24 publications

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“…Conjugation systems in Gram-negative bacteria elaborate translocation channels and conjugative pili, whose coordinated activities mediate transfer of cognate MGEs by a process requiring direct cell-to-cell contact (Achtman, 1975;Achtman et al, 1978;Arutyunov and Frost, 2013). Assembly of both organelles requires nearly the same set of T4SS subunits, but the relationship of the channel and pilus is not yet structurally or functionally defined.…”

Section: Discussionmentioning

confidence: 99%

Two pKM101‐encoded proteins, the pilus‐tip protein TraC and Pep, assemble on the Escherichia coli cell surface as adhesins required for efficient conjugative DNA transfer

González-Rivera¹,

Khara²,

Awad³

et al. 2018

Molecular Microbiology

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Summary Mobile genetic elements (MGEs) encode type IV secretion systems (T4SSs) known as conjugation machines for their transmission between bacterial cells. Conjugation machines are composed of an envelope-spanning translocation channel, and those functioning in Gram-negative species additionally elaborate an extracellular pilus to initiate donor-recipient cell contacts. We report that pKM101, a self-transmissible MGE functioning in the Enterobacteriaceae, has evolved a second target cell attachment mechanism. Two pKM101-encoded proteins, the pilus-tip adhesin TraC and a protein termed Pep, are exported to the cell surface where they interact and also form higher-order complexes appearing as distinct foci or patches around the cell envelope. Surface-displayed TraC and Pep are required for efficient conjugative transfer, ‘extracellular complementation’ potentially involving intercellular protein transfer, and activation of a Pseudomonas aeruginosa type VI secretion system. Both proteins are also required for bacteriophage PRD1 infection. TraC and Pep are exported across the outer membrane by a mechanism potentially involving the β-barrel assembly machinery. The pKM101 T4SS thus deploys alternative routing pathways for delivery of TraC to the pilus tip or both TraC and Pep to the cell surface. We propose that T4SS-encoded, pilus-independent attachment mechanisms maximize the probability of MGE propagation and might be widespread among this translocation superfamily.

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Section: Discussionmentioning

confidence: 99%

Two pKM101‐encoded proteins, the pilus‐tip protein TraC and Pep, assemble on the Escherichia coli cell surface as adhesins required for efficient conjugative DNA transfer

González-Rivera¹,

Khara²,

Awad³

et al. 2018

Molecular Microbiology

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“…The F‐plasmid in the donor directs the expression of one to three pili, rigid pilin fibers sticking out from the cell wall. Cell contact is followed by pilus retraction (or not, Lawley et al, 2004), and the formation of a mating bridge by the fusion of a portion of cell membranes (Achtman et al, 1978). In the donor cell, DNA transfer is initiated at the oriT region of the plasmid, where one of the DNA strands is cleaved, and then gradually separated from the complementary strand while being transferred to the recipient through the mating bridge.…”

Section: Horizontal Gene Transfermentioning

confidence: 99%

Horizontal Gene Transfer on Surfaces in Natural Porous Media: Conjugation and Kinetics

Massoudieh

Mathew

Lambertini

et al. 2007

Vadose Zone Journal

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The transfer of genetic material among bacteria in the environment has been linked to a range of important phenomena related to bacterial adaptation and evolution, including bioremediation capability, metal tolerance, antibiotic resistance by pathogens in the environment, and gene fl ow from genetically modifi ed microorganisms. Transfer of genetic material can occur among microorganisms present in both the planktonic and attached states. Given the propensity of organisms to exist in sessile communities under oligotrophic conditions, and that such conditions typify the subsurface, study of subsurface gene transfer phenomena should include processes and kinetics for a range of sessile community structures, from reversibly attached single cells to mature biofi lms, as well as planktonic communities. This study very briefl y reviewed horizontal, primarily conjugative, gene transfer in natural porous media, and the kinetics used to date to describe conjugative gene transfer in both planktonic (aqueous suspension) and sessile (surface associated) communities. The mathematics so far used to describe the kinetics of conjugation have developed largely from experimental observations of planktonic gene transfer, and are absent of time lags that occur between gene transfer events or plasmid stability that appear experimentally. We develop a novel formulation of delay-difference equations for gene transfer for attached-state microbes using an exposure-time approach to account for lags.

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“…This was established by separating conjugating cells in an EcoRI-resthcted mating by blending at 12 min and then incubating bacteria for up to 28 min prior to selection for transconjugants. SDS and nalidixic acid were added to the blended bacteria to prevent further conjugation: these agents block de novo formation of mating aggregates and inhibit the DNA transfer potential of drug-sensitive donors, respectively (Achtman et at., 1978;Witletts and Wilkins, 1984). The treatments arrested the increase of transconjugants in the restricted mating, indicating in turn that EcoRI-evasion is dependent on prolonged donor activity.…”

Section: Restriction Of Dna Transferred By Conjugation and Transformamentioning

confidence: 99%

Evasion of type I and type II DNA restriction systems by Incl1 plasmid Collb‐P9 during transfer by bacterial conjugation

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Thomas

Wilkins

1992

Molecular Microbiology

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Transmission of unmodified plasmid CoIIb-P9 by bacterial conjugation is markedly resistant to restriction compared with transfer by transformation. One process allowing evasion of type I and II restriction systems involves conjugative transfer of multiple copies of the plasmid. A more specialized evasion mechanism requires the Ard (alleviation of restriction of DNA) system encoded by CoIIb. The ard gene is transferred early in conjugation and specifically alleviates DNA restriction by all known families of type I enzyme, including EcoK. CoIIb has no effect on EcoK modification but this activity is impaired by multicopy recombinant plasmids supporting overexpression of ard. Genetic evidence shows that Ard protects CoIIb from EcoK restriction following conjugative transfer and that this protection requires expression of the gene on the immigrant plasmid. It is proposed that carriage of ard facilitates transfer of CoIIb between its natural enterobacterial hosts and that the route of DNA entry is important to the restriction-evasion mechanism.

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Cell-cell interactions in conjugating Escherichia coli: role of F pili and fate of mating aggregates

Cited by 95 publications

References 24 publications

Two pKM101‐encoded proteins, the pilus‐tip protein TraC and Pep, assemble on the Escherichia coli cell surface as adhesins required for efficient conjugative DNA transfer

Two pKM101‐encoded proteins, the pilus‐tip protein TraC and Pep, assemble on the Escherichia coli cell surface as adhesins required for efficient conjugative DNA transfer

Horizontal Gene Transfer on Surfaces in Natural Porous Media: Conjugation and Kinetics

Evasion of type I and type II DNA restriction systems by Incl1 plasmid Collb‐P9 during transfer by bacterial conjugation

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