Characterization of the Genes Encoding <scp>d</scp> -Amino Acid Transaminase and Glutamate Racemase, Two <scp>d</scp> -Glutamate Biosynthetic Enzymes of <i>Bacillus sphaericus</i> ATCC 10208

Abstract

In Bacillus sphaericus and other Bacillus spp., D-amino acid transaminase has been considered solely responsible for biosynthesis of D-glutamate, an essential component of cell wall peptidoglycan, in contrast to the glutamate racemase employed by many other bacteria. We report here the cloning of the dat gene encoding D-amino acid transaminase and the glr gene encoding a glutamate racemase from B. sphaericus ATCC 10208. The glr gene encodes a 28. 8-kDa protein with 40 to 50% sequence identity to the glutamate racemases of Lactobacillus, Pediococcus, and Staphylococcus species. The dat gene encodes a 31.4-kDa peptide with 67% primary sequence homology to the D-amino acid transaminase of the thermophilic Bacillus sp. strain YM1.