Neurospora crassa cytochrome

LS, K.H.D. Lederer, F. (1983). On the presence of a heme-binding domain homologous to cytochrome b5 in Neurospora crassa assimilatory nitrate reductase. The EMBO Journal 2, 1909-14. 

The assimilatory enzyme from the mold Neurospora crassa has been intensively studied for over two decades, particularly by Nason and his collaborators. Thus, Nason and Evans (39) identified FAD as a prosthetic group in the enzyme Nicholas, Nason, and McElroy (40) showed that molybdenum was required for the synthesis of nitrate reductase Nicholas and Nason (41) suggested its presence in the enzyme Garrett and Nason (42) showed that a b-type cytochrome (cytochrome 6557) co-purifies with this nitrate reductase and Nason et al. (11) suggested, from in vitro complementation experiments with nitrate reductaseless mutants, that the enzyme consists of at least two components required for activity. These workers have suggested that the electron transfer pathway is ... 

Weiss, H., and Kolb, H. J., 1979, Isolation of mitochondrial succinate ubiquinone reductase, cytochrome c reductase and cytochrome c oxidase from Neurospora crassa using nonionic detergent, Eur. J. Biochem. 99 139nl49. 

NDMA is mutagenic for Escherichia coli, Salmonella typhimurium, and Neurospora crassa. It can produce mitotic recombination in Sacharoyus cerevesiae species, recessive lethal mutations in Drosophilla melanogaster, and chromosomal aberrations in mammalian cells. Mutagenic responses in bacterial cells are dependent upon the addition of a mammalian drug metabolism system (specific form of cytochrome P450). 

Attar, R.M., E. Grotewold, G.E. Taccioli, G.O. Aisemberg, H.N. Torres, and N.D. Judewicz (1989). A cycloheximide-inducible gene of Neurospora crassa belongs to the cytochrome P450 superfamily Nucleic Acids Res. 17, 7535-7536. 

There are no plasma membrane-bound enzymes whose activities are known to be specifically and sufficiently altered to account for growth Inhibition by the sterol inhibitors at sub-MIC doses. A likely candidate is chitin synthetase, but the activity of this enzyme is not reduced in fact, sterol inhibitor-treated fungi contain more glucosamine polymers than controls. However, the altered deposition of chitin (see above references) may reflect a discontinuity between cytoskeletal elements which are believed to be involved in cell wall formation and the plasma membrane, but it is unlikely that this is at the root of growth inhibition since a wall-less slime mutant of Neurospora crassa is as sensitive as the wild-type strain to propiconazole (57TI Cytochrome oxidase and microsomal ATPase are inhibited by high concentrations (10 5,... 

Further data were obtained by Weiss et al. (1971) with Neurospora crassa. Chromatography of mitochondrial protein labeled in vivo in the presence of cycloheximide (CH), yielded fractions containing difilerent amounts of radioactivity. The fraction of highest specific radioactivity was pure and enzymically active cytochrome oxidase. Separation of the polypeptide chains of this enzyme by SDS gel electrophoresis revealed five protein bands of which, in the presence of CH, only one polypeptide was highly labeled. Similar results were obtained with cytochrome oxidase from Locusta migratoria (Weiss et al, 1972). Here seven polypeptide chains were obtained. One, with a molecular weight of about 19,000, was labeled in the presence of CH and may be a product of mitochondrial protein synthesis. 

N.r. of Neurospora crassa has M, 228,000. A N.r. mutant (Neurospora crassa nit-3) produces a subunit of N.r. containing cytochrome and Mo (M, 160,000) this does not react with NAD(P)H, but transfers electrons to nitrate from exogenous FADH2 or reduced methyl viologen. The other component is produced by Neurospora crassa nit-I it is unable to reduce nitrate, but catalyses the reduction of cytochrome c by NAD(P)H. 

Although the biogenesis of cytochrome b has not been closely examined in yeast, studies on Neurospora crassa have shown that in this organism, both the mitochondrial and cytoplasmic protein-synthesizing systems contribute to the cytochrome b complex. Cytochrome b probably contains two polypeptide types of molecular weight 30,000. Inhibition studies have shown that only one of these is translated on mitochondrial ribosomes (see Chapter 5). 

Biogenesis of Cytochrome Oxidase and Cytochrome b in Neurospora crassa... 

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