The research in this proposal is designed to test the hypothesis that bacterial transporters with diverse substrates have a common mechanism of action, i.e. the choice of substrate is mediated by subtle differences in amino acid sequences of the transporters. The specific aims are: 1) to isolate spontaneous mutants of various transporters with altered substrate specificity. This will be done by selection of transporter mutants on minimal media plates with different carbon sources, such as maltose, sucrose, lactose, melibiose, and raffinose; 2) to determine the DNA sequence of the isolated mutants that have altered substrates specificities; and 3) to demonstrate that the newly acquired function exists in the mutants by measuring transport activity. The results from this research will be used in the development of a RUI proposal to test structure/function predictions of transporter proteins that will be submitted at a later date.
