[43] Isolation and properties of the branched-chain 2-keto acid and pyruvate dehydrogenase multienzyme complex from Bacillus subtilis

1988 ◽  
pp. 330-342 ◽  
Author(s):  
Richard N. Perham ◽  
Peter N. Lowe
Keyword(s):  
Bacillus Subtilis ◽  
Pyruvate Dehydrogenase ◽  
Multienzyme Complex ◽  
Keto Acid ◽  
Branched Chain

scholarly journals Dual role of a single multienzyme complex in the oxidative decarboxylation of pyruvate and branched-chain 2-oxo acids in Bacillus subtilis

1983 ◽  
Vol 215 (1) ◽  
pp. 133-140 ◽  
Author(s):  
P N Lowe ◽  
J A Hodgson ◽  
R N Perham
Keyword(s):  
Bacillus Subtilis ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Oxidative Decarboxylation ◽  
Multienzyme Complex ◽  
Complex Activity ◽  
Acid Dehydrogenase ◽  
Branched Chain ◽  
Acid Dehydrogenase Complex ◽  
Dehydrogenase Complex

The pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase activities of Bacillus subtilis were found to co-purify as a single multienzyme complex. Mutants of B. subtilis with defects in the pyruvate decarboxylase (E1) and dihydrolipoamide dehydrogenase (E3) components of the pyruvate dehydrogenase complex were correspondingly affected in branched-chain 2-oxo acid dehydrogenase complex activity. Selective inhibition of the E1 or lipoate acetyltransferase (E2) components in vitro led to parallel losses in pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complex activity. The pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complexes of B. subtilis at the very least share many structural components, and are probably one and the same. The E3 component appeared to be identical for the pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complexes in this organism and to be the product of a single structural gene. Long-chain branched fatty acids are thought to be essential for maintaining membrane fluidity in B. subtilis, and it was observed that the ace (pyruvate dehydrogenase complex) mutant 61142 was unable rapidly to take up acetoacetate, unlike the wild-type, indicative of a defect in membrane permeability. A single pyruvate dehydrogenase and branched-chain 2-oxo acid dehydrogenase complex can be seen as an economical means of supplying two different sets of essential metabolites.

Genetic mapping of bfmA mutation causing fatty acid deficiency in Bacillus subtilis

1993 ◽  
Vol 39 (6) ◽  
pp. 629-633 ◽  
Author(s):  
Takashi Akamatsu ◽  
Hideaki Moriyama ◽  
Toshi Kaneda
Keyword(s):  
Bacillus Subtilis ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Acid Decarboxylase ◽  
Subtilis Strain ◽  
Decarboxylase Activity ◽  
Keto Acid ◽  
Branched Chain ◽  
Fatty Acid Deficiency

Bacillus subtilis strain 626, defective in the bfmA gene, is a derivative of B. subtilis strain 168 and requires branched short-chain carboxylic acids for growth. Branched-chain 2-keto acid decarboxylase activity and fatty acid synthesis in B. subtilis strain 626 were 14 and 7%, respectively, of their levels in strain 626-2R, a spontaneously reverted strain. These results indicate that the bfmA mutation is in either the branched-chain 2-keto acid decarboxylase gene itself or its controlling gene. Thus, primer synthesis from the 2-keto acid substrate in strain 626 is defective, causing a deficiency in fatty acid synthesis. A bfmA mutation was transferred to a suitable genetic background and analysed. The bfmA strain, CACl, was competent and motile, and required 50 μM CaCl2 or 5 μM FeCl3 for growth on glucose minimal agar plates. The bfmA gene was mapped between glyC (320°) and ctrA (325°) and estimated to be at 320° by protoplast fusion and PBS1 phage transduction.Key words: Bacillus subtilis, 2-keto acid decarboxylase, bfmA mutation, chromosome location, protoplast transformation, PBI phage transduction.

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