Sorting of peroxisomal and mitochondrial carnitine acetyltransferase isozymes in the diploid yeast, Candida tropicalis.
Peroxisomal and mitochondrial carnitine acetyltransferase (CAT; EC 2.3.1.7) isozymes are synthesized from the first and second ATG codons of the open reading frame of one gene, Candida tropicalis CAT. Primer extension analysis and RNase protection assay revealed that the peroxisomal CAT, initiating at the second AUG codon of the transcripts, was synthesized by a translational readthrough of the first AUG codon of the open reading frame. When C. tropicalis CAT was introduced into the other yeast, Saccharomyces cerevisiae, 5' ends of transcripts were similar to those observed in C. tropicalis. Peroxisomal and mitochondrial CAT isozymes were strongly suggested to occur by the alternative initiation of translation, chiefly dependent on the structure or sequence context of the region from the 5' end to the second AUG codon; their transcripts harbored sufficient information to bring about alternative initiation of translation in both yeasts. Sorting of peroxisomal and mitochondrial CAT isozymes to their own compartment was carried out by their own targeting sequences, but, before transportation to their destination, their biosyntheses were regulated by alternative initiation of translation.
Tanaka
A
A
Laboratory of Applied Biological Chemistry, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. atsuo@sbchem.kyoto-u.ac.jp
Ueda
M
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D002175:Candida / Q000201:enzymology*; D002332:Carnitine O-Acetyltransferase / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D020675:Peroxisomes / Q000201:enzymology*; D014158:Transcription, Genetic
D007527:Isoenzymes; D002332:Carnitine O-Acetyltransferase