Residues 137 and 153 of XylS influence contacts with the C-terminal domain of the RNA polymerase alpha subunit.

XylS and XylS1 are transcriptional regulators that stimulate transcription from the Pm promoter for the meta-cleavage pathway operon for alkylbenzoate degradation. These regulators that differ in five amino acids interact with alpha-CTD domain of RNA polymerase. These interactions take place preferentially through residues 291 in XylS and 289 in XylS1. Substitution at position 137 and 153 in XylS influence the interactions with alpha-CTD because single and double mutants in these positions turned preferential interactions to residue 289. Copyright 2001 Academic Press.