Structural homology between rbs repressor and ribose binding protein implies functional similarity

Abstract

The deduced amino acid sequence of the rbs repressor, RbsR, of Escherichia coli is homologous over its C‐terminal 272 residues to the entire sequence of the periplasmic ribose binding protein. RbsR is also homologous to a family of bacterial repressor proteins including LacI. This implies that the structure of the repressor consists of a two‐domain binding protein portion attached to a DNA‐binding domain having the four‐helix structure of the LacI headpiece. The implications of these relationships to the mechanism of this class of repressors are discussed.