THE DLT OPERON IN THE BIOSYNTHESIS OF D-ALANYL-LIPOTEICHOIC ACID IN LACTOBACILLUS-CASEI

The D-alanine incorporation system allows Lactobacillus casei to modul ate the chemical properties of lipoteichoic acid (LTA) and hence contr ol its proposed functions, i.e., regulation of autolysin action, metal ion binding, and the electromechanical properties of the cell wall, T he system requires the D-alanine-D-alanyl carrier protein ligase (Dcl) and the D-alanyl carrier protein (Dcp), Our results indicate that the genes for these proteins are encoded in the dlt operon and that this operon contains at least 2 other genes, dltB and dltD, The aim of this paper is to describe the genetic organization of the operon, the role of the D-alanyl carrier protein, and the function of the putative pro tein encoded by dltB in the intramembranal translocation of the activa ted D-alanine.