Open AccessCompetence Regulation by Oxygen Availability and by Nox Is Not Related to Specific Adjustment of Central Metabolism in Streptococcus pneumoniae
Author(s) -
Sabine ChapuyRegaud,
F Duthoit,
Laurence Malfroy-Mastrorillo,
Pierre Gourdon,
Nic D. Lindley,
MarieClaude Trombe
Publication year - 2001
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.183.9.2957-2962.2001
Subject(s) - biology , biochemistry , glycolysis , metabolism , oxidase test , dehydrogenase , lactate dehydrogenase , nadph oxidase , streptococcus pneumoniae , enzyme , antibiotics
In Streptococcus pneumoniae oxygen availability is a major determinant for competence development in exponentially growing cultures. NADH oxidase activity is required for optimal competence in cultures grown aerobically. The implication of oxidative metabolism and more specifically of Nox on central metabolism has been examined. Glycolytic flux throughout exponential growth revealed homolactic fermentation with a lactate production/glucose utilization ratio close to 2, whatever the aerobiosis level of the culture. Loss-of-function mutations in nox, which encodes NADH oxidase, did not change this trait. Consistently, mRNA levels of glyceraldehyde-3-phosphate dehydrogenase, L-lactate dehydrogenase, pyruvate oxidase, and NADH oxidase remained comparable to wild-type levels, as did the specific activities of key enzymes which control central metabolism. Competence regulation by oxygen involving the NADH oxidase activity is not due to significant modification of carbon flux through glycolysis. Failure to obtain loss-of-function mutation in L-ldh, which encodes the L-lactate dehydrogenase, indicates its essential role in pneumococci whatever their growth status.