Tactic interaction of ribose-binding protein with the membrane receptor Trg

Abstract

To investigate the interaction between ribose-binding protein (REP) and Trg chemosensory transducer, we have isolated suppressor mutations in REP for the trg-8 mutation that causes a specific defect in chemotactic response to ribose, In addition, nonchemotactic mutations of REP were isolated, The mutations were characterized by measuring binding affinity, uptake rate, and chemotactic response in capillary, They exhibit altered responses to ribose, while one of them show additional transport defects, In order to quantitatively monitor the interaction of REP with Trg, an assay using the chimeric receptor Trz1 (Baumgartner et al., 1994) was performed, indicating changes of the mutant REP in their affinities to the receptor, The results imply that the interactive surface on REP involves the regions around the binding cleft including residues 65 and 192 on the three-dimensional structure of REP.