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Journal of Bacteriology, April 2000, p. 2113-2118, Vol. 182, No. 8
Department of Natural Resource Sciences,
McGill University, Ste.-Anne-de-Bellevue, Québec H9X
3V9,1 and Department of Biology,
University of Waterloo, Waterloo, Ontario N2L
3G1,2 Canada
Received 22 October 1999/Accepted 22 January 2000
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.
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Requirement for the Enzymes Acetoacetyl Coenzyme A Synthetase and
Poly-3-Hydroxybutyrate (PHB) Synthase for Growth of Sinorhizobium
meliloti on PHB Cycle Intermediates
*
Corresponding author. Mailing address: Department of
Biology, University of Waterloo, 200 University Ave. West, Waterloo, ON
N2L 3G1, Canada. Phone: (519) 888-4567, ext. 5606. Fax: (519) 746-0614. E-mail: tcharles{at}uwaterloo.ca.
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