Abstract
BackgroundPathogenic yersiniae, including Y. pestis, share a type III secretion system (T3SS) that is composed of a secretion machinery, a set of translocation proteins, a control system, and six Yop effector proteins including YpkA and YopJ. The cyclic AMP receptor protein (CRP), a global regulator, was recently found to regulate the laterally acquired genes (pla and pst) in Y. pestis. The regulation of T3SS components by CRP is unknown.ResultsThe sycO, ypkA and yopJ genes constitute a single operon in Y. pestis. CRP specifically binds to the promoter-proximate region of sycO, and represses the expression of the sycO-ypkA-yopJ operon. A single CRP-dependent promoter is employed for the sycO-ypkA-yopJ operon, but two CRP binding sites (site 1 and site 2) are detected within the promoter region. A CRP box homologue is found in site 1 other than site 2. The determination of CRP-binding sites, transcription start site and core promoter element (-10 and -35 regions) promotes us to depict the structural organization of CRP-dependent promoter, giving a map of CRP-promoter DNA interaction for sycO-ypkA-yopJ.ConclusionThe sycO-ypkA-yopJ operon is under the direct and negative regulation of CRP in Y. pestis. The sycO-ypkA-yopJ promoter-proximate regions are extremely conserved in Y. pestis, Y. pseudotuberculosis and Y. enterocolitica. Therefore, data presented here can be generally applied to the above three pathogenic yersiniae.
Highlights
Pathogenic yersiniae, including Y. pestis, share a type III secretion system (T3SS) that is composed of a secretion machinery, a set of translocation proteins, a control system, and six Yop effector proteins including Yersinia protein kinase A (YpkA) and Yersinia outer protein J (YopJ)
The sycO, ypkA and yopJ genes constitute a single operon The RT-PCR assay indicated that the sycO, ypkA and yopJ genes were transcribed as a single primary RNA (Fig. 1), and thereby these three genes constituted a single operon in Y. pestis Microtus strain 201
cyclic AMP receptor protein (CRP) greatly represses transcription of the sycO-ypkAyopJ operon Our previous cDNA microarray analysis showed that the transcription of sycO, ypkA and yopJ was repressed by CRP [4]
Summary
Pathogenic yersiniae, including Y. pestis, share a type III secretion system (T3SS) that is composed of a secretion machinery, a set of translocation proteins, a control system, and six Yop effector proteins including YpkA and YopJ. The cyclic AMP receptor protein (CRP), a global regulator, was recently found to regulate the laterally acquired genes (pla and pst) in Y. pestis. The three pathogenic Yersinia species, Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica, share a type III secretion system (T3SS) that is composed of a secretion machinery, a set of translocation proteins, a control system, and six Yop effector proteins [1,2]. The cyclic AMP receptor protein (CRP) is a global regulator that controls the transcription initiation for more than 100 bacterial genes/operons [3]. The CRPpromoter DNA interaction is crucial for the regulation of target genes
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