InterPro domain: IPR035472

RpiR contains a SIS (Sugar ISomerase) domain, which is found in many phosphosugar isomerases and phosphosugar binding proteins. In E. coli, RpiR negatively regulates the expression of rpiB gene. Both rpiB and rpiA are ribose phosphate isomerases that catalyze the reversible reactions of ribose 5-phosphate into ribulose 5-phosphate [ 1 ].

This domain is also found in other members of the RpiR family of transcriptional regulators, such as MurR [ 2 ] and in uncharacterised proteins of the UPF0309 family.

1. Ribose catabolism of Escherichia coli: characterization of the rpiB gene encoding ribose phosphate isomerase B and of the rpiR gene, which is involved in regulation of rpiB expression. J. Bacteriol. 178, 1003-11
2. The transcriptional factors MurR and catabolite activator protein regulate N-acetylmuramic acid catabolism in Escherichia coli. J. Bacteriol. 190, 6598-608