Previous Article | Next Article ![]()
J. Bacteriol., Oct 1997, 6285-6293, Vol 179, No. 20
N Goupil-Feuillerat, M Cocaign-Bousquet, JJ Godon, SD Ehrlich and P Renault
The alpha-acetolactate decarboxylase gene aldB is clustered with the genes
for the branched-chain amino acids (BCAA) in Lactococcus lactis subsp.
lactis. It can be transcribed with BCAA genes under isoleucine regulation
or independently of BCAA synthesis under the control of its own promoter.
The product of aldB is responsible for leucine sensibility under valine
starvation. In the presence of more than 10 microM leucine, the
alpha-acetolactate produced by the biosynthetic acetohydroxy acid synthase
IlvBN is transformed to acetoin by AldB and, consequently, is not available
for valine synthesis. AldB is also involved in acetoin formation in the
2,3-butanediol pathway, initiated by the catabolic acetolactate synthase,
AlsS. The differences in the genetic organization, the expression, and the
kinetics parameters of these enzymes between L. lactis and Klebsiella
terrigena, Bacillus subtilis, or Leuconostoc oenos suggest that this
pathway plays a different role in the metabolism in these bacteria. Thus,
the alpha- acetolactate decarboxylase from L. lactis plays a dual role in
the cell: (i) as key regulator of valine and leucine biosynthesis, by
controlling the acetolactate flux by a shift to catabolism; and (ii) as an
enzyme catalyzing the second step of the 2,3-butanediol pathway.
Copyright © 1997, American Society for Microbiology
Dual role of alpha-acetolactate decarboxylase in Lactococcus lactis subsp. lactis
Laboratoire de Genetique Microbienne, Institut National de la Recherche Agronomique, Jouy en Josas, France.
This article has been cited by other articles:
| Appl. Environ. Microbiol. | Infect. Immun. | Eukaryot. Cell |
|---|---|---|
| Mol. Cell. Biol. | J. Virol. | Microbiol. Mol. Biol. Rev. |
| ALL ASM JOURNALS |