Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:1.6.99.5 (
NADH dehydrogenase
)
2,135
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Many commensal oral streptococci generate H
2
O
2
via pyruvate oxidase (SpxB) to inhibit the growth of competing bacteria like Streptococcus mutans, a major cariogenic species. In Streptococcus sanguinis SK36 (SK36) and Streptococcus gordonii
DL1
(
DL1
), spxB expression and H
2
O
2
release are subject to carbon catabolite repression by the catabolite control protein A (CcpA). Surprisingly, ccpA deletion mutants of SK36 and
DL1
fail to inhibit S. mutans despite their production of otherwise inhibitory levels of H
2
O
2
. Using H
2
O
2
-deficient spxB deletion mutants of SK36 and
DL1
, it was subsequently discovered that both strains confer protection in trans to other bacteria when H
2
O
2
is added exogenously. This protective effect depends on the direct detoxification of H
2
O
2
by the release of pyruvate. The pyruvate dependent protective effect is also present in other spxB-encoding streptococci, such as the pneumococcus, but is missing from spxB-negative species like S. mutans. Targeted and transposon-based mutagenesis revealed Nox (putative H
2
O-forming
NADH dehydrogenase
) as an essential component required for pyruvate release and oxidative protection, while other genes such as sodA and dps play minor roles. Furthermore, pyruvate secretion is only detectable in aerobic growth conditions at biofilm-like cell densities and is responsive to CcpA-dependent catabolite control. This ability of spxB-encoding streptococci reveals a new facet of the competitive interactions between oral commensals and pathobionts and provides a mechanistic basis for the variable levels of inhibitory potential observed among H
2
O
2
-producing strains of commensal oral streptococci.
...
PMID:Pyruvate secretion by oral streptococci modulates hydrogen peroxide dependent antagonism. 3198 75
