PMID:20083612

Citation	Serna, A, Espinosa, E, Camacho, EM and Casadesús, J (2010) Regulation of bacterial conjugation in microaerobiosis by host-encoded functions ArcAB and sdhABCD. Genetics 184:947-58
Abstract	The virulence plasmid of Salmonella enterica (pSLT) is an F-like conjugative plasmid. High rates of pSLT transfer occur in the mammalian gut, a microaerobic environment. In this study, we describe genetic screens for host-encoded activators and repressors of the transfer operon (tra) of pSLT. We show that the transcription factor ArcA is an activator of conjugation, especially under microaerobiosis. In turn, succinate dehydrogenase (SdhABCD) is a repressor of mating in aerobiosis. ArcA binds upstream of the main tra promoter (p(traY)) and activates tra transcription, as previously described in F, R1, and R100. In the absence of ArcA, transfer of pSLT decreased 7-fold in aerobiosis and >100-fold in microaerobiosis. In aerobiosis, ArcA activates the traY promoter in an ArcB-independent manner, as described in other F-like plasmids. In microaerobiosis, however, the ArcB sensor is necessary for activation of p(traY). Lack of Sdh causes a >20-fold increase in pSLT transfer in aerobiosis, but has little effect under microaerobiosis. Sdh inhibits conjugal transfer by reducing traJ transcription, probably in an indirect manner. In turn, the sdhCDAB operon is repressed by the ArcAB system under microaerobiosis. Hence, the ArcAB two-component system of S. enterica stimulates pSLT transfer under microaerobiosis by two concerted actions: activation of the tra operon and repression of the sdhCDAB operon.
Links	PubMed PMC2865929 Online version:10.1534/genetics.109.109918
Keywords	Aerobiosis; Bacterial Outer Membrane Proteins/genetics; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Chromosomes, Bacterial/genetics; Conjugation, Genetic; Gene Expression Regulation, Bacterial/drug effects; Gene Fusion; Mutagenesis; Operon/genetics; Oxygen/pharmacology; Plasmids/genetics; Promoter Regions, Genetic/genetics; RNA, Messenger/genetics; Reverse Transcriptase Polymerase Chain Reaction; Salmonella enterica/drug effects; Salmonella enterica/enzymology; Salmonella enterica/genetics; Salmonella enterica/metabolism; Succinate Dehydrogenase/metabolism; Transcription Factors/genetics; Transcription Factors/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
DICDI:ABCD2		GO:0006955: immune response	ECO:0000314:		P		Figure 4: Diagram of the traJ-traY border in the pSLT plasmid, indicating the position of ptraY, the region homologous to ArcA binding sites of other F-like plasmids, and the locations of the primers used for PCR amplification.	complete CACAO 10734

References

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