General Organization of Rhizobium phaseoli nif Plasmids

Leemans, J.; Soberón, Gloria; Cevallos, Miguel A.; Fernández, Leonor; Pardo, Marco Aurelio; Vega, Humberto de la; Flores, Margarita Avilés; Quinto, Carmen; Palacios, Rafael

doi:10.1007/978-94-009-6923-0_357

Cited by 8 publications

(3 citation statements)

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“… a The recipient in crosses 1, 2 5, 6, and 7 was UIA143, and CFN2001 (Leemans et al, 1984 ) in crosses 3 and 4 . b Transfer frequency is expressed as number of transconjugants per donor cell, and is the average of at least three experiments .…”

Section: Resultsmentioning

confidence: 99%

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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

et al. 2015

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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.

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Section: Resultsmentioning

confidence: 99%

“… a The recipient in crosses 1, 2 5, 6, and 7 was UIA143, and CFN2001 (Leemans et al, 1984 ) in crosses 3 and 4 . …”

Section: Resultsmentioning

confidence: 99%

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

et al. 2015

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“…To construct GR64-6, Tn 5 -GDYN-labeled-pSfr64a was introduced into GR64-4. CFN2001 is a derivative of R. etli CFN42 that lacks the pSym (pRet42d), and the self-transmissible plasmid pRet42a [ 37 ]. This strain was used as receptor to select transconjugants carrying the Tn 5mob -labeled pSym of GR64 (CFN2001-1), the Tn 5mob -labeled pSym of GR64 and Tn 5 -GDYN-labeled pRet42a of R. etli CFN42 (CFN2001-2), and both plasmids of GR64 (CFN2001-3).…”

Section: Methodsmentioning

confidence: 99%

The conjugative plasmid of a bean-nodulating Sinorhizobium fredii strain is assembled from sequences of two Rhizobium plasmids and the chromosome of a Sinorhizobiumstrain

et al. 2011

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BackgroundBean-nodulating Rhizobium etli originated in Mesoamerica, while soybean-nodulating Sinorhizobium fredii evolved in East Asia. S. fredii strains, such as GR64, have been isolated from bean nodules in Spain, suggesting the occurrence of conjugative transfer events between introduced and native strains. In R. etli CFN42, transfer of the symbiotic plasmid (pRet42d) requires cointegration with the endogenous self-transmissible plasmid pRet42a. Aiming at further understanding the generation of diversity among bean nodulating strains, we analyzed the plasmids of S. fredii GR64: pSfr64a and pSfr64b (symbiotic plasmid).ResultsThe conjugative transfer of the plasmids of strain GR64 was analyzed. Plasmid pSfr64a was self-transmissible, and required for transfer of the symbiotic plasmid. We sequenced pSfr64a, finding 166 ORFs. pSfr64a showed three large segments of different evolutionary origins; the first one presented 38 ORFs that were highly similar to genes located on the chromosome of Sinorhizobium strain NGR234; the second one harbored 51 ORFs with highest similarity to genes from pRet42d, including the replication, but not the symbiosis genes. Accordingly, pSfr64a was incompatible with the R. etli CFN42 symbiotic plasmid, but did not contribute to symbiosis. The third segment contained 36 ORFs with highest similarity to genes localized on pRet42a, 20 of them involved in conjugative transfer. Plasmid pRet42a was unable to substitute pSfr64a for induction of pSym transfer, and its own transfer was significantly diminished in GR64 background. The symbiotic plasmid pSfr64b was found to differ from typical R. etli symbiotic plasmids.ConclusionsS. fredii GR64 contains a chimeric transmissible plasmid, with segments from two R. etli plasmids and a S. fredii chromosome, and a symbiotic plasmid different from the one usually found in R. etli bv phaseoli. We infer that these plasmids originated through the transfer of a symbiotic-conjugative-plasmid cointegrate from R. etli to a S. fredii strain, and at least two recombination events among the R. etli plasmids and the S. fredii genome. As in R. etli CFN42, the S. fredii GR64 transmissible plasmid is required for the conjugative transfer of the symbiotic plasmid. In spite of the similarity in the conjugation related genes, the transfer process of these plasmids shows a host-specific behaviour.

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Impaired nitrogen fixation and glutamine synthesis in methionine sulfoximine sensitive (MSs) mutants of Rhizobium phaseoli

1985

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General Organization of Rhizobium phaseoli nif Plasmids

Cited by 8 publications

References 1 publication

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

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

The conjugative plasmid of a bean-nodulating Sinorhizobium fredii strain is assembled from sequences of two Rhizobium plasmids and the chromosome of a Sinorhizobiumstrain

Impaired nitrogen fixation and glutamine synthesis in methionine sulfoximine sensitive (MSs) mutants of Rhizobium phaseoli

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