Structural basis of specific TraD–TraM recognition during F plasmid‐mediated bacterial conjugation

Lu, Jun; Wong, Jillian W.; Edwards, Ross A.; Manchak, Jan; Frost, Laura S.; Glover, J. N. Mark

doi:10.1111/j.1365-2958.2008.06391.x

Cited by 67 publications

(98 citation statements)

References 47 publications

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“…An X-ray structure of the TraD C-terminal tail bound to TraM shows that the TraD tail forms extensive contacts with the TraM monomer and, furthermore, that as many as four TraD C-terminal tails can bind a single TraM tetramer. These findings imply that a TraD hexamer establishes extensive contacts with TraM in vivo, thus forming the basis of a highly specific relaxosome-T4CP interaction (181). In this system, the T4CP carries the unstructured C-terminal tail responsible for F plasmid recognition and binding.…”

Section: Substrate Receptor Activitymentioning

confidence: 93%

Biological Diversity of Prokaryotic Type IV Secretion Systems

Martı́nez

Christie

2009

Microbiol Mol Biol Rev

621

780

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SUMMARY Type IV secretion systems (T4SS) translocate DNA and protein substrates across prokaryotic cell envelopes generally by a mechanism requiring direct contact with a target cell. Three types of T4SS have been described: (i) conjugation systems, operationally defined as machines that translocate DNA substrates intercellularly by a contact-dependent process; (ii) effector translocator systems, functioning to deliver proteins or other macromolecules to eukaryotic target cells; and (iii) DNA release/uptake systems, which translocate DNA to or from the extracellular milieu. Studies of a few paradigmatic systems, notably the conjugation systems of plasmids F, R388, RP4, and pKM101 and the Agrobacterium tumefaciens VirB/VirD4 system, have supplied important insights into the structure, function, and mechanism of action of type IV secretion machines. Information on these systems is updated, with emphasis on recent exciting structural advances. An underappreciated feature of T4SS, most notably of the conjugation subfamily, is that they are widely distributed among many species of gram-negative and -positive bacteria, wall-less bacteria, and the Archaea. Conjugation-mediated lateral gene transfer has shaped the genomes of most if not all prokaryotes over evolutionary time and also contributed in the short term to the dissemination of antibiotic resistance and other virulence traits among medically important pathogens. How have these machines adapted to function across envelopes of distantly related microorganisms? A survey of T4SS functioning in phylogenetically diverse species highlights the biological complexity of these translocation systems and identifies common mechanistic themes as well as novel adaptations for specialized purposes relating to the modulation of the donor-target cell interaction.

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Section: Substrate Receptor Activitymentioning

confidence: 93%

Biological Diversity of Prokaryotic Type IV Secretion Systems

Martı́nez

Christie

2009

Microbiol Mol Biol Rev

621

780

View full text Add to dashboard Cite

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“…In the E. coli F plasmid transfer system, the TraD F receptor recruits the F plasmid in part through binding of the relaxosome subunit TraM. An X-ray structure of the TraD-TraM interaction revealed specific contacts between TraD F 's C-terminal acidic residues and TraM (20,92). Genetic studies confirmed that the TraD F -TraM F interaction promotes efficient F plasmid transfer and also that this interaction strongly inhibits transfer of the MOBQ plasmid RSF1010 through the F T4SS (20,93).…”

Section: Discussionmentioning

confidence: 99%

“…The F plasmid-encoded TraD T4CP and many T4CPs associated with effector translocator systems possess a fourth, C-terminal domain (CTD) of variable lengths and sequence compositions. Studies of TraD's CTD established its critical role in recruitment of the F plasmid to the F-encoded T4SS (20), but the contributions of CTDs to effector protein trafficking have not been evaluated (2).…”

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confidence: 99%

Chimeric Coupling Proteins Mediate Transfer of Heterologous Type IV Effectors through the Escherichia coli pKM101-Encoded Conjugation Machine

Whitaker¹,

Berry²,

Rosenthal³

et al. 2016

J Bacteriol

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Bacterial type IV secretion systems (T4SSs) are composed of two major subfamilies, conjugation machines dedicated to DNA transfer and effector translocators for protein transfer. We show here that the Escherichia coli pKM101-encoded conjugation system, coupled with chimeric substrate receptors, can be repurposed for transfer of heterologous effector proteins. The chimeric receptors were composed of the N-terminal transmembrane domain of pKM101-encoded TraJ fused to soluble domains of VirD4 homologs functioning in Agrobacterium tumefaciens, Anaplasma phagocytophilum, or Wolbachia pipientis. A chimeric receptor assembled from A. tumefaciens VirD4 (VirD4 At ) mediated transfer of a MOBQ plasmid (pML122) and A. tumefaciens effector proteins (VirE2, VirE3, and VirF) through the pKM101 transfer channel. Equivalent chimeric receptors assembled from the rickettsial VirD4 homologs similarly supported the transfer of known or candidate effectors from rickettsial species. These findings establish a proof of principle for use of the dedicated pKM101 conjugation channel, coupled with chimeric substrate receptors, to screen for translocation competency of protein effectors from recalcitrant species. Many T4SS receptors carry sequence-variable C-terminal domains (CTDs) with unknown function. While VirD4 At and the TraJ/VirD4 At chimera with their CTDs deleted supported pML122 transfer at wild-type levels, ⌬CTD variants supported transfer of protein substrates at strongly diminished or elevated levels. We were unable to detect binding of VirD4 At 's CTD to the VirE2 effector, although other VirD4 At domains bound this substrate in vitro. We propose that CTDs evolved to govern the dynamics of substrate presentation to the T4SS either through transient substrate contacts or by controlling substrate access to other receptor domains. IMPORTANCEBacterial type IV secretion systems (T4SSs) display striking versatility in their capacity to translocate DNA and protein substrates to prokaryotic and eukaryotic target cells. A hexameric ATPase, the type IV coupling protein (T4CP), functions as a substrate receptor for nearly all T4SSs. Here, we report that chimeric T4CPs mediate transfer of effector proteins through the Escherichia coli pKM101-encoded conjugation system. Studies with these repurposed conjugation systems established a role for acidic C-terminal domains of T4CPs in regulating substrate translocation. Our findings advance a mechanistic understanding of T4CP receptor activity and, further, support a model in which T4SS channels function as passive conduits for any DNA or protein substrates that successfully engage with and pass through the T4CP specificity checkpoint.T he type IV secretion systems (T4SSs) display striking versatility among the known bacterial translocation systems in their capacity to translocate DNA and protein substrates to bacterial or eukaryotic target cells (1, 2). Members of one major T4SS subfamily, the conjugation machines, mediate transfer of mobile DNA elements and are responsible for widespr...

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“…The VirB4 tree showed a more scattered distribution of relaxase families, especially among MPF T plasmids. From a functional point of view, although T4CPs interact with components of both the relaxosome and the T4SS, the T4CP-relaxosome interactions seem to be more system specific (94,96,97,101). Besides, T4CP-encoding genes are usually adjacent to the genes coding for the relaxosome components (50,57), with gene order conservation being another sign of coevolution and functional relatedness.…”

Section: Coevolution Of Mobilization and Conjugationmentioning

confidence: 99%

Mobility of Plasmids

Smillie

Garcillán-Barcia

Francia

et al. 2010

Microbiol Mol Biol Rev

955

1,054

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International audiencePlasmids are key vectors of horizontal gene transfer and essential genetic engineering tools. They code for genes involved in many aspects of microbial biology, including detoxication, virulence, ecological interactions, and antibiotic resistance. While many studies have decorticated the mechanisms of mobility in model plasmids, the identification and characterization of plasmid mobility from genome data are unexplored. By reviewing the available data and literature, we established a computational protocol to identify and classify conjugation and mobilization genetic modules in 1,730 plasmids. This allowed the accurate classification of proteobacterial conjugative or mobilizable systems in a combination of four mating pair formation and six relaxase families. The available evidence suggests that half of the plasmids are nonmobilizable and that half of the remaining plasmids are conjugative. Some conjugative systems are much more abundant than others and preferably associated with some clades or plasmid sizes. Most very large plasmids are nonmobilizable, with evidence of ongoing domestication into secondary chromosomes. The evolution of conjugation elements shows ancient divergence between mobility systems, with relaxases and type IV coupling proteins (T4CPs) often following separate paths from type IV secretion systems. Phylogenetic patterns of mobility proteins are consistent with the phylogeny of the host prokaryotes, suggesting that plasmid mobility is in general circumscribed within large clades. Our survey suggests the existence of unsuspected new relaxases in archaea and new conjugation systems in cyanobacteria and actinobacteria. Few genes, e.g., T4CPs, relaxases, and VirB4, are at the core of plasmid conjugation, and together with accessory genes, they have evolved into specific systems adapted to specific physiological and ecological contexts

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Structural basis of specific TraD–TraM recognition during F plasmid‐mediated bacterial conjugation

Cited by 67 publications

References 47 publications

Biological Diversity of Prokaryotic Type IV Secretion Systems

Biological Diversity of Prokaryotic Type IV Secretion Systems

Chimeric Coupling Proteins Mediate Transfer of Heterologous Type IV Effectors through the Escherichia coli pKM101-Encoded Conjugation Machine

Mobility of Plasmids

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