IBBM   21076
INSTITUTO DE BIOTECNOLOGIA Y BIOLOGIA MOLECULAR
Unidad Ejecutora - UE
artículos
Título:
Genes encoding conserved hypothetical proteins localized in the conjugative transfer region of plasmid pRet42a from Rhizobium etli CFN42 participate in modulating transfer and affect conjugation from different donors
Autor/es:
EUNICE LÓPEZ-FUENTES; GONZALO A. TORRES TEJERIZO; LAURA CERVANTES; SUSANA BROM
Revista:
Frontiers in Microbiology
Editorial:
Frontiers
Referencias:
Año: 2015 vol. 5 p. 1 - 10
Resumen:
Among sequenced genomes, it is common to find a high proportion of genes
encoding proteins that cannot be assigned a known function. In
bacterial genomes, genes related to a similar function are often located
in contiguous regions. The presence of genes encoding conserved
hypothetical proteins (chp) in such a region may suggest that they are
related to that particular function. Plasmid pRet42a from Rhizobium etli
CFN42 is a conjugative plasmid containing a segment of approximately 30
Kb encoding genes involved in conjugative transfer. In addition to
genes responsible for Dtr (DNA transfer and replication), Mpf (Mating
pair formation) and regulation, it has two chp-encoding genes
(RHE_PA00163 and RHE_PA00164) and a transcriptional regulator
(RHE_PA00165). RHE_PA00163 encodes an uncharacterized protein conserved
in bacteria that presents a COG4634 conserved domain, and RHE_PA00164
encodes an uncharacterized conserved protein with a DUF433 domain of
unknown function. RHE_PA00165 presents a HTH_XRE domain, characteristic
of DNA-binding proteins belonging to the xenobiotic response element
family of transcriptional regulators. Interestingly, genes similar to
these are also present in transfer regions of plasmids from other
bacteria. To determine if these genes participate in conjugative
transfer, we mutagenized them and analyzed their conjugative phenotype. A
mutant in RHE_PA00163 showed a slight (10 times) but reproducible
increase in transfer frequency from Rhizobium donors, while mutants in RHE_PA00164 and RHE_PA00165 lost their ability to transfer the plasmid from some Agrobacterium
donors. Our results indicate that the chp-encoding genes located among
conjugation genes are indeed related to this function. However, the
participation of RHE_PA00164 and RHE_PA00165 is only revealed under very
specific circumstances, and is not perceived when the plasmid is
transferred from the original host. RHE_PA00163 seems to be a
fine-tuning modulator for conjugative transfer.