title: Rhodothermus marinus: a thermophilic bacterium producing dimeric and hexameric citrate synthase isoenzymes.
abstract: Two separate citrate synthases from the extremely thermophilic bacterium Rhodothermus marinus have been identified and purified. One of the enzymes is a hexameric protein and is the first thermostable, hexameric citrate synthase to be isolated. The other is a dimeric enzyme, which is also thermostable but possesses both citrate synthase and 2-methyl citrate synthase activities. 2-Methyl citrate synthase uses propionyl-coenzyme A as one of its substrates and in Escherichia coli, for example, it has been implicated in the metabolism of propionate. However, no growth of R. marinus was observed using minimal medium with propionate as the sole carbon source, and both hexameric and dimeric enzymes were produced irrespective of whether propionate was included in the growth medium. The data are discussed with respect to the evolutionary relationships between the known hexameric and dimeric citrate synthases and 2-methyl citrate synthase.
authors.affiliation: Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, Sweden. eva.nordberg@biotek.lu.se
authors.forename: Karlsson Eva
authors.initials: KE
authors.lastname: Nordberg
authors.forename: Maher
authors.initials: M
authors.lastname: Abou-Hachem
authors.forename: Olle
authors.initials: O
authors.lastname: Holst
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Danson
authors.forename: David W
authors.initials: DW
authors.lastname: Hough
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology*; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002950:Citrate (si)-Synthase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D019281:Dimerization; D004795:Enzyme Stability; D006358:Hot Temperature; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D007527:Isoenzymes; D046911:Macromolecular Substances; D002950:Citrate (si)-Synthase