Cytosolic aspartate aminotransferase encoded by the AAT2 gene is targeted to the peroxisomes in oleate-grown Saccharomyces cerevisiae

• Published in: European journal of biochemistry Vol. 247; no. 3; pp. 972 - 980
• Main Authors: Verleur, N, Elgersma, Y, Roermund, C.W.T. van, Tabak, H.F, Wanders, R.J.A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.08.1997
• Subjects: Amino Acid Sequence; aspartate aininotransferase; Aspartate Aminotransferases - biosynthesis; Aspartate Aminotransferases - genetics; Base Sequence; Biological Transport; Cloning, Molecular; Cytosol - enzymology; Enzyme Induction; Microbodies - enzymology; Microscopy, Electron; Molecular Sequence Data; NAD(H) redox shuttle; Oleic Acid - pharmacology; peroxisome; plant biochemistry; plant physiology; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Subcellular Fractions - enzymology; subcellular localization
• ISSN: 0014-2956; 1432-1033
• DOI: 10.1111/j.1432-1033.1997.00972.x

Fatty acid beta-oxidation in peroxisomes requires the continued uptake of fatty acids or their derivatives into peroxisomes and export of beta-oxidation products plus oxidation of NADH to NAD. In an earlier study we provided evidence for the existence of an NAD(H) redox shuttle in which peroxisomal malate dehydrogenase plays a pivotal role. In analogy to the NAD(H)-redox-shuttle systems in mitochondria we have investigated whether a malate/aspartate shuttle is operative in peroxisomes. The results described in this paper show that peroxisomes of oleate-grown Saccharomyces cerevisiae contain aspartate aminotransferase (AAT) activity. Whereas virtually all cellular AAT activity was peroxisomal in oleate-grown cells, we found that in glucose-grown cells most of the AAT activity resided in the cytosol. We demonstrate that the gene AA72 codes for the cytosolic and peroxisomal AAT activities. Disruption of the AA72 gene did not affect growth on oleate. Furthermore beta-oxidation of palmitate was normal. These results indicate that AAT2 is not essential for the peroxisomal NAD(H) redox shuttle.