Regulation and oxidation of two large monofunctional catalases.
The two Neurospora crassa catalase genes cat-1 and cat-3 were shown to encode Cat-1 and Cat-3 large monofunctional catalases. cat-1 and cat-3 genes are regulated differentially during the asexual life cycle and under stress conditions. A stepwise increase in catalase activity occurs during conidiation. Conidia have 60 times more catalase activity than exponentially growing hyphae. Cat-1 activity was predominant in conidia, during germination and early exponential growth. It was induced during prestationary growth and by ethanol or heat shock. Cat-3 activity was predominant during late exponential growth and at the start of the conidiation process. It was induced under stress conditions, such as H(2)O(2), paraquat, cadmium, heat shock, uric acid, and nitrate treatment. In general, Cat-1 activity was associated with nongrowing cells and Cat-3 activity with growing cells. The Cat-3 N-terminus sequence indicates that this catalase is processed and presumably secreted. Paraquat caused modification and degradation of Cat-1. Under heat shock both Cat-1 and Cat-3 were modified and degraded and Cat-1 was resynthesized. Paraquat and heat shock effects were observed only in the presence of air and are probably related to in vivo generation of singlet oxygen. Purified Cat-3 was modified with a photosensitizing reaction in which singlet oxygen is produced.
Michán
Shaday
S
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City, DF.
Lledías
Fernando
F
Baldwin
James D
JD
Natvig
Donald O
DO
Hansberg
Wilhelm
W
D000332:Aerobiosis; D000595:Amino Acid Sequence; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle; D016384:Consensus Sequence; D004790:Enzyme Induction / Q000187:drug effects; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005800:Genes, Fungal; D006358:Hot Temperature; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D018384:Oxidative Stress; D010269:Paraquat / Q000494:pharmacology; D010777:Photochemistry; D012331:RNA, Fungal / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D012100:Reproduction, Asexual / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D026082:Singlet Oxygen / Q000378:metabolism
D005656:Fungal Proteins; D007527:Isoenzymes; D012331:RNA, Fungal; D012333:RNA, Messenger; D026082:Singlet Oxygen; D002374:Catalase; D010269:Paraquat