Molecular biology and bacterial secondary transporters

Bacterial permeases form a family of membrane proteins that actively transport nutrients according to a cation-solute cotransport mechanism. The purpose of this review is to consider the many perspectives offered by in vitro recombinant DNA and molecular biology techniques for analysis of structure-function relationships. In the first part of this review, the kinetic parameters that permit characterization of either the partial steps or the overall transport reaction are summarized. We then list the molecular properties (protein sequence and composition, secondary structure, biochemical identification) of the carriers readily available on cloning a structural gene into plasmids. Finally, the usefulness of site-specific, oligonucleotide-directed mutagenesis for investigation of the functional importance of given residues (cysteins and histidines) or domains of the transport proteins is illustrated.