SEQUENCE AND ORGANIZATION OF GENES ENCODING ENZYMES INVOLVED IN PYRUVATE METABOLISM IN MYCOPLASMA-CAPRICOLUM

The region of the genome of Mycoplasma capricolum upstream of the port ion encompassing the genes for Enzymes zymes I and IIA(glc) of the pho sphoenolpyruvate:sugar phosphotransferase system (PTS) was cloned and sequenced. Examination of the sequence revealed open reading frames co rresponding to numerous genes involved with the oxidation of pyruvate. The deduced gene organization is naox (encoding NADH oxidase)-lplA (e ncoding lipoate-protein ligase)-odpA (encoding pyruvate dehydrogenase EI alpha)-odpB (encoding pyruvate dehydrogenase EI beta)-odp2 (encodin g pyruvate dehydrogenase EII)-dldH (encoding dihydrolipoamide dehydrog enase)-pta (encoding phosphotransacetylase)-ack (encoding acetate kina se)-orfA (an unknown open reading frame)-kdtB-ptsI-crr. Analysis of th e DNA sequence suggests that the naox and lplA genes are part of a sin gle operon, odpA and odpB constitute an additional operon, odp2 and dl dH a third operon, and pfa and ack an additional transcription unit. P hylogenetic analyses of the protein products of the odpA and odpB gene s indicate that they are most similar to the corresponding proteins fr om Mycoplasma genitalium, Acholeplasma laidlawii, and Gram-positive or ganisms. The product of the odp2 gene contains a single lipoyl domain, as is the case with the corresponding proteins from M. genitalium and numerous other organisms. An evolutionary tree places the M. capricol um odp2 gene product in close relationship to the corresponding protei ns from A. laidlawii and M. genitalium. The dldH gene encodes an unusu al form of dihydrolipoamide dehydrogenase that contains an aminotermin al extension corresponding to a lipoyl domain, a property shared by th e corresponding proteins from Alcaligenes eutrophus and Clostridium ma gnum. Aside from that feature, the protein is related phylogenetically to the corresponding proteins from A. laidlawii and M. genitalium. Th e phosphotransacetylase from M. capricolum is related most closely to the corresponding protein from M. genitalium and is distinguished easi ly from the enzymes from Escherichia coil and Haemophilus influenzae b y the absence of the characteristic amino-terminal extension. The acet ate kinase from M. capricolum is related evolutionarily to the homolog ous enzyme from M. genitalium. Map position comparisons of genes encod ing proteins involved with pyruvate metabolism show that, whereas all the genes are clustered in M. capricolum, they are scattered in M. gen italium.