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

摘要

In Bacillus sphaericus and other Bacillusspp., 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 glrgene encodes a 28.8-kDa protein with 40 to 50% sequence identity to the glutamate racemases of Lactobacillus,Pediococcus, and Staphylococcus species. Thedat 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.