title: Expression of acetoacetyl-CoA thiolase isozyme genes of n-alkane-assimilating yeast, Candida tropicalis: isozymes in two intracellular compartments are derived from the same genes.
abstract: In the n-alkane-assimilating yeast Candida tropicalis, there are two isozymes of acetoacetyl-CoA thiolase, peroxisomal acetoacetyl-CoA thiolase (peroxisomal Thiolase I), and cytosolic acetoacetyl-CoA thiolase (cytosolic Thiolase I). We have previously isolated two genes (CT-T1A and CT-T1B) which encode Thiolase I. In order to compare the expressed products of Thiolase I isozyme-encoding genes in C. tropicalis, cytosolic Thiolase I was first purified from glucose-grown C. tropicalis in which the proliferation of peroxisomes and the expression of peroxisomal Thiolase I were repressed. Cytosolic Thiolase I was virtually identical to peroxisomal Thiolase I in molecular mass, kinetic and immunochemical properties, and primary structure at the N-terminus. Amino acid sequence analysis revealed that cytosolic Thiolase I was the mixture of products of two genes (CT-T1A and CT-T1B), as in the case of the peroxisomal enzyme. CT-T1A and CT-T1B were expressed independently in the yeast Saccharomyces cerevisiae and the recombinant proteins were purified. Recombinant Thiolase IA and IB exhibited practically identical enzymatic properties to cytosolic and peroxisomal Thiolase Is from C. tropicalis. These results revealed that cytosolic Thiolase I and peroxisomal Thiolase I were encoded not by different genes, but by the same genes (CT-T1A and CT-T1B) and are present as a mixture of products expressed by both genes, although their subcellular localizations are different.
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University.
authors.forename: N
authors.initials: N
authors.lastname: Kanayama
authors.forename: Y
authors.initials: Y
authors.lastname: Himeda
authors.forename: H
authors.initials: H
authors.lastname: Atomi
authors.forename: M
authors.initials: M
authors.lastname: Ueda
authors.forename: A
authors.initials: A
authors.lastname: Tanaka
mesh_terms: D000101:Acetyl-CoA C-Acetyltransferase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D002175:Candida / Q000201:enzymology* / Q000235:genetics*; D003600:Cytosol / Q000201:enzymology; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000302:isolation & purification; D015870:Gene Expression; D005800:Genes, Fungal; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008830:Microbodies / Q000201:enzymology; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D007527:Isoenzymes; D011994:Recombinant Proteins; D000101:Acetyl-CoA C-Acetyltransferase