Biosynthesis of o-succinylbenzoic acid in Bacillus subtilis: identification of menD mutants and evidence against the involvement of the alpha-ketoglutarate dehydrogenase complex.
The biosynthesis of o-succinylbenzoic acid (OSB), the first aromatic intermediate involved in the biosynthesis of menaquinone (vitamin K2) is demonstrated for the first time in the gram-positive bacterium Bacillus subtilis. Cell extracts were found to contain isochorismate synthase, 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylic acid (SHCHC) synthase-alpha-ketoglutarate decarboxylase and o-succinylbenzoic acid synthase activities. An odhA mutant which lacks the decarboxylase component (usually termed E1, EC 1.2.4.2, oxoglutarate dehydrogenase [lipoamide]) of the alpha-ketoglutarate dehydrogenase complex was found to synthesize SHCHC and form succinic semialdehyde-thiamine pyrophosphate. Thus, the presence of an alternate alpha-ketoglutarate decarboxylase activity specifically involved in menaquinone biosynthesis is established for B. subtilis. A number of OSB-requiring mutants were also assayed for the presence of the various enzymes involved in the biosynthesis of OSB. All mutants were found to lack only the SHCHC synthase activity.
Palaniappan
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Department of Biological Sciences, Northern Illinois University, DeKalb 60115.
Taber
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Meganathan
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D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D002827:Chorismic Acid / Q000378:metabolism; D003510:Cyclohexanes; D053138:Cyclohexenes; D007655:Ketoglutarate Dehydrogenase Complex / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation; D007652:Oxo-Acid-Lyases / Q000096:biosynthesis; D010654:Phenylbutyrates / Q000378:metabolism*; D012459:Salicylates / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology; D013386:Succinates / Q000378:metabolism; D014812:Vitamin K / Q000494:pharmacology
C087010:2-succinyl-6-hydroxycyclohexa-2,4-diene-1-carboxylic acid; D003510:Cyclohexanes; D053138:Cyclohexenes; D010654:Phenylbutyrates; D012459:Salicylates; D013386:Succinates; D014812:Vitamin K; C052985:isochorismic acid; C013691:o-succinylbenzoic acid; D007655:Ketoglutarate Dehydrogenase Complex; C060510:2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase; D007652:Oxo-Acid-Lyases; D002827:Chorismic Acid