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Quorum-dependent mannopine-inducible conjugative transfer of an Agrobacterium opine-catabolic plasmid.

ABSTRACT: The Ti plasmid in Agrobacterium tumefaciens strain 15955 carries two alleles of traR that regulate conjugative transfer. The first is a functional allele, called traR, that is transcriptionally induced by the opine octopine. The second, trlR, is a nonfunctional, dominant-negative mutant located in an operon that is inducible by the opine mannopine (MOP). Based on these findings, we predicted that there exist wild-type agrobacterial strains harboring plasmids in which MOP induces a functional traR and, hence, conjugation. We analyzed 11 MOP-utilizing field isolates and found five where MOP induced transfer of the MOP-catabolic element and increased production of the acyl-homoserine lactone (acyl-HSL) quormone. The transmissible elements in these five strains represent a set of highly related plasmids. Sequence analysis of one such plasmid, pAoF64/95, revealed that the 176-kb element is not a Ti plasmid but carries genes for catabolism of MOP, mannopinic acid (MOA), agropinic acid (AGA), and the agrocinopines. The plasmid additionally carries all of the genes required for conjugative transfer, including the regulatory genes traR, traI, and traM. The traR gene, however, is not located in the MOP catabolism region. The gene, instead, is monocistronic and located within the tra-trb-rep gene cluster. A traR mutant failed to transfer the plasmid and produced little to no quormone even when grown with MOP, indicating that TraRpAoF64/95 is the activator of the tra regulon. A traM mutant was constitutive for transfer and acyl-HSL production, indicating that the anti-activator function of TraM is conserved.

SUBMITTER: Wetzel ME

PROVIDER: S-EPMC3957693 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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Quorum-dependent mannopine-inducible conjugative transfer of an Agrobacterium opine-catabolic plasmid.

Wetzel Margaret E ME Kim Kun-Soo KS Miller Marilyn M Olsen Gary J GJ Farrand Stephen K SK

Journal of bacteriology 20131220 5

The Ti plasmid in Agrobacterium tumefaciens strain 15955 carries two alleles of traR that regulate conjugative transfer. The first is a functional allele, called traR, that is transcriptionally induced by the opine octopine. The second, trlR, is a nonfunctional, dominant-negative mutant located in an operon that is inducible by the opine mannopine (MOP). Based on these findings, we predicted that there exist wild-type agrobacterial strains harboring plasmids in which MOP induces a functional tra ...[more]

PMID: 24363349

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Dataset Information

Quorum-dependent mannopine-inducible conjugative transfer of an Agrobacterium opine-catabolic plasmid.

Publications

Quorum-dependent mannopine-inducible conjugative transfer of an Agrobacterium opine-catabolic plasmid.

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