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Transcriptional Regulation of the assT-dsbL-dsbI Gene Cluster in Salmonella enterica Serovar Typhi IMSS-1 Depends on LeuO, H-NS, and Specific Growth Conditions

Gallego-Hernández, A. L., Hernández-Lucas, I., De la Cruz, M. A., Olvera, L., Morett, E., Medina-Aparicio, L., Ramírez-Trujillo, J. A., Vázquez, A., Fernández-Mora, M., Calva, E.
Journal of bacteriology 2012 v.194 no.9 pp. 2254-2264
Salmonella enterica subsp. enterica serovar Typhi, disulfide bonds, operon, regulatory proteins, transcription (genetics)
The assT gene encodes an arylsulfate sulfotransferase, an enzyme that catalyzes sulfuryl transfer from phenolic sulfate to a phenolic acceptor. In Salmonella enterica serovar Typhi IMSS-1, the assT gene is located upstream of the dsbL and dsbI genes, which are involved in a disulfide bond formation required for its activation. The assT-dsbL-dsbI gene cluster forms an operon transcribed by a LeuO-dependent promoter, in rich medium A (MA). Interestingly, in the absence of cloned leuO and in a ΔleuO background, two transcription start sites were detected for assT and two for dsbL-dsbI in minimal medium. The H-NS nucleoid protein repressed the expression of the assT-dsbL-dsbI LeuO-dependent operon, as well as of the assT transcriptional units. Thus, the expression of the assT-dsbL-dsbI gene cluster depends on the global regulatory proteins LeuO and H-NS, as well as on specific growth conditions.