Glr, a glutamate racemase, supplies D-glutamate to both peptidoglycan synthesis and poly-gamma-glutamate production in gamma-PGA-producing Bacillus subtilis.
Poly-gamma-glutamate (gamma-PGA)-producing Bacillus subtilis contains two glutamate racemase genes, glr and yrpC, as does gamma-PGA-nonproducing B. subtilis strain 168. glr and yrpC on the chromosome of gamma-PGA-producing strain r22 were separately disrupted by means of gene replacement with an erythromycin resistance determinant. yrpC-disruption caused no effects on growth or gamma-PGA-production, whereas glr was disrupted only when an exogenous glr copy was present on a plasmid. In addition, the D-glutamate content of gamma-PGA produced by the yrpC-disruptant was the same as that produced by the parental strain r22. Glr in strain r22 is therefore responsible for the supply of D-glutamate to the synthesis of both peptidoglycan and gamma-PGA. Consistent with this idea, glr was transcribed actively during the exponential growth phase for peptidoglycan synthesis and continuously at a low, but distinct, level during the stationary phase for gamma-PGA production, whereas yrpC was transcribed at a very low level throughout growth. Phylogenetic analysis of glutamate racemases from eubacteria showed that YrpC is distinct from other glutamate racemases.
Kada
Shigeki
S
Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, 113-8657, Japan.
Nanamiya
Hideaki
H
Kawamura
Fujio
F
Horinouchi
Sueharu
S
D000591:Amino Acid Isomerases / Q000235:genetics* / Q000378:metabolism; D001412:Bacillus subtilis / Q000201:enzymology* / Q000254:growth & development; D003001:Cloning, Molecular; D005516:Food Microbiology; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D018698:Glutamic Acid / Q000378:metabolism*; D016296:Mutagenesis; D010457:Peptidoglycan / Q000096:biosynthesis*; D010802:Phylogeny; D010957:Plasmids; D011099:Polyglutamic Acid / Q000096:biosynthesis*; D014158:Transcription, Genetic
D010457:Peptidoglycan; D011099:Polyglutamic Acid; D018698:Glutamic Acid; D000591:Amino Acid Isomerases; C062292:glutamate racemase