期刊
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
卷 362, 期 3, 页码 646-650出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.bbrc.2007.08.019
关键词
Bacillus subtilis; D-Glutamate; glutamate racemase; poly-gamma-glutamate; genetic design
Bacillus subtilis possesses two glutamate racemase isozymes, RacE and YrpC. For the first time, we succeeded in constructing glutamate racemase-gene disruptants of B. subtilis. Phenotypic analysis of their D-glutamate auxotrophy indicated that the RacE-type glutamate racemase is important for ensuring maximum growth rate but dispensable. The YrpC-type glutamate racemase probably operates as an anaplerotic enzyme for RacE, especially under liquid culture conditions. We found novel applicability of RacE-less mutants inheriting only a marginal activity for endogenous D-glutamate supply, viz. the employment for the in vivo identification Of D-glutamate-consurning systems. In fact, the genetic induction of a POly-gamma-glutamate synthetic system led a RacE-less mutant to severe growth suppression, which was overcome in the presence of a high concentration of exogenous D-glutamate. The results indicate that a significant amount Of D-glutamatc is consumed during poly-glutamate biosynthesis. To our knowledge, this is the first report of conditional D-glutamate auxotrophy for R subtilis. (c) 2007 Elsevier Inc. All rights reserved.
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