Genetic regulation of the tricarboxylate transport operon (tctI) of Salmonella typhimurium.

AUTOR(ES)

Widenhorn, K A

RESUMO

Tricarboxylates are transported into Salmonella typhimurium by a binding protein-dependent transport system known as TctI. Genetically, it comprises three structural genes, tctCBA, as well as a fourth gene of unknown function (tctD), which is transcribed divergently from tctC (K. A. Widenhorn, J. M. Somers, and W. W. Kay, J. Bacteriol. 170:3223-3227, 1988). Deletions in tctD strongly reduced expression of tctC or of tctC-lacZ transcriptional fusions; however, expression was restored when tctD was present in trans. Expression of tctD-lacZ transcriptional fusions was strongly repressed in the presence of D-glucose but could be alleviated by the addition of cyclic AMP. Furthermore, transcription of tctD was found not to be autogenously regulated. Thus, tctD is considered to be regulated by catabolite repression and encodes a transcriptional activator of tctCBA expression. From the DNA sequence of tctD, the predicted gene product was hydrophilic and shared distinct homologies with other globally regulated transcriptional activators such as OmpR and NtrC.

Documentos Relacionados

• Expression of the divergent tricarboxylate transport operon (tctI) of Salmonella typhimurium.
• Fine-structure genetic map of the maltose transport operon of Salmonella typhimurium.
• Cloning and properties of the Salmonella typhimurium tricarboxylate transport operon in Escherichia coli.
• Characterization of transcriptional regulation of the kdp operon of Salmonella typhimurium.
• Regulation of L-cystine transport in Salmonella typhimurium.