A biochemical basis for obligate methylotrophy: properties of a mutant of Pseudomonas AM1 lacking 2-oxoglutarate dehydrogenase.
Pseudomonas AMI is a facultative methylotroph which grows on a wide range of carbon compounds. A mutant of Pseudomonas AMI (ICT4I) grew only on C1 compounds and is thus an artificial obligate methylotroph. Measurements of activities of the components of the 2-oxoglutarate dehydrogenase complex suggest that the E2 component (dihydrolipoamide transsuccinylase) is not functional. All other tricarboxylic acid cycle enzymes were present with activities comparable to those in wild-type Pseudomonas AMI and cytochrome levels were unchanged in the mutant. Suspensions of the mutant oxidized pyruvate, lactate, beta-hydroxybutyrate, acetoacetate and 2-oxoglutarate at very low rates. By contrast, C1 compounds were oxidized at the same rate as in wild-type bacteria. Two revertants of ICT4I which regained 2-oxyoglutarate dehydrogenase activity also regained the ability to oxidize and grow on the same substrates as wild-type bacteria. It is concluded that lack of 2-oxoglutarate dehydrogenase may well be the basis of obligate methylotrophy in some bacteria.
D002474:Cell-Free System; D002952:Citric Acid Cycle; D003580:Cytochromes / Q000096:biosynthesis; D005561:Formates / Q000378:metabolism; D007655:Ketoglutarate Dehydrogenase Complex / Q000096:biosynthesis* / Q000378:metabolism; D007658:Ketone Oxidoreductases / Q000096:biosynthesis*; D000432:Methanol / Q000378:metabolism; D008744:Methylamines / Q000378:metabolism; D009154:Mutation; D010070:Oxalates / Q000378:metabolism; D010101:Oxygen Consumption; D011549:Pseudomonas / Q000201:enzymology* / Q000378:metabolism; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism
D003580:Cytochromes; D005561:Formates; D008744:Methylamines; D010070:Oxalates; D011768:Pyruvate Dehydrogenase Complex; D007658:Ketone Oxidoreductases; D007655:Ketoglutarate Dehydrogenase Complex; D000432:Methanol