CTA1 encodes catalase A, which is involved in hydrogen peroxide detoxification in the peroxisomal and mitochondrial matrices (2, 3). In peroxisomes, the primary source of hydrogen peroxide is that produced during fatty acid beta-oxidation (2, 4, and reviewed in 1). In mitochondria, hydrogen peroxide is produced by the superoxide dismutases Sod1p and Sod2p in defending against reactive oxygen species (5). Catalases break down hydrogen peroxide into dioxygen (02) and water molecules (reviewed in 6). Cta1p activity is important during oxidative stress response and in protecting proteins against oxidative inactivation (7, 8). Cta1p activity is also increased during caloric restriction and during oxidative stress caused by the processes of aging, acid stress adaptation, and thermotolerance (9, 10, 11).

Catalase A is a homotetramer with one heme group and one NADP(H) cofactor binding site per subunit (4). Transcription of CTA1 is regulated in response to oleic acid, glucose, heme, and oxygen, (12, 13, 14). This transcriptional response is mediated by the transcriptional activators Adr1p, Oaf1p, Rtg1p, and Rtg2p via binding to overlapping ORE and UAS1 elements in the CTA1 promoter (15, 16 and references therein).

The S. cerevisiae genome encodes a second catalase, cytoplasmic catalase T (encoded by CTT1), and although these two enzymes are functionally similar, Cta1p is more similar in sequence to the peroxiosomal catalases from the cow Bos taurus and the pathogenic yeast Candida tropicalis than it is to Ctt1p (17).

Last updated: 2008-07-02