Requirement for the enzymes acetoacetyl coenzyme A synthetase and poly-3-hydroxybutyrate (PHB) synthase for growth of Sinorhizobium meliloti on PHB cycle intermediates.
We have identified two Sinorhizobium meliloti chromosomal loci affecting the poly-3-hydroxybutyrate degradation pathway. One locus was identified as the gene acsA, encoding acetoacetyl coenzyme A (acetoacetyl-CoA) synthetase. Analysis of the acsA nucleotide sequence revealed that this gene encodes a putative protein with a molecular weight of 72,000 that shows similarity to acetyl-CoA synthetase in other organisms. Acetyl-CoA synthetase activity was not affected in cell extracts of glucose-grown acsA::Tn5 mutants; instead, acetoacetyl-CoA synthetase activity was drastically reduced. These findings suggest that acetoacetyl-CoA synthetase, rather than CoA transferase, activates acetoacetate to acetoacetyl-CoA in the S. meliloti poly-3-hydroxybutyrate cycle. The second locus was identified as phbC, encoding poly-3-hydroxybutyrate synthase, and was found to be required for synthesis of poly-3-hydroxybutyrate deposits.
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Department of Natural Resource Sciences, McGill University, Ste. -Anne-de-Bellevue, Québec H9X 3V9, Canada.
Driscoll
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Charles
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D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D006885:Hydroxybutyrates / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D011091:Polyesters / Q000378:metabolism*; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D016962:Sinorhizobium meliloti / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D000094122:Polyhydroxybutyrates
D000217:Acyltransferases; D003066:Coenzyme A Ligases; D006885:Hydroxybutyrates; D011091:Polyesters; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C060970:poly-beta-hydroxybutyrate polymerase; C023747:acetoacetyl-CoA synthetase