Characterization of OpuA, a glycine-betaine uptake system of Lactococcus lactis.

A Lactococcus lactis glycine-betaine transport system was identified by functional complementation of an Escherichia coli proP proU mutant with a gene library from L. lactis sbsp. cremoris. The cloned locus forms an operon highly homologous to opuA, encoding a glycine-betaine uptake system of Bacillus subtilis. Disruption of opuA in L. lactis abolished protection by glycine-betaine against elevated osmolarity. OpuA belongs to the so-called "ABC...