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M Grenson

Publications and source records attributed to M Grenson.

At least 37 records · Page 2Linked to original sources
PubMed1982

Pleiotropic deficiency in nitrogen-uptake systems and derepression of nitrogen-catabolic enzymes in npr-1 mutants of Saccharomyces cerevisiae.

The npr-1 mutation has two types of effects in Saccharomyces cerevisiae. On one hand, several nitrogen-catabolic enzymes are derepressed in the presence of ammonia, glutamine, or asparagine, which provoke their repression in a wild-type strain. On the other hand, the activity of several ammonia-sensitive permeases is decreased (from 50-100% depending on the permease considered) in npr-1 cells, independently of the nitrogen source used for growth. Our results favour the idea that the primary effect of the npr-1 mutation is on the permeases, and that the derepression of the enzymes is a consequence of the reduced uptake rate of the repressing nitrogen compounds. Hence, the product of the npr-1 gene appears to be directly involved in the development of the activity of a set of permeases which transport nitrogen compounds and which are regulated by nitrogen effectors.

Amino Acid Transport Systems↗
PubMed1979

Organization and expression of a two-gene cluster in the arginine biosynthesis of Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, argB and argC define two adjacent and complementing loci, with mutants defective in two consecutive steps of arginine biosynthesis: N-acetylglutamate kinase (AG-kinase) and N-acetylglutamyl-phosphate reductase (AGPreductase). These enzymic activities are readily separated by ammonium sulfate fractionation or Sephadex G-200 chromatography. This suggests that each activity is carried in vivo by a different protein. The synthesis of the two enzymes is coordinately regulated, with an 85-fold difference in specific activities between fully repressed and fully derepressed cells. Missence mutations of the argB locus are defective in AGkinase only. Nonsense mutations in the argB locus are defective in both activities. Missense and nonsense mutations in the argC locus are defective in AGPreductase, with a few alleles also showing a reduced level of AGkinase. These data are best explained by assuming that argB and argC are two genes transcribed as a single messenger from argB to argC. This messenger produces in vivo two distinct proteins corresponding to the argB and argC gene products, either because translation can be initiated at the beginning of both genes, or because a large polypeptide is specifically cut in vivo to yield the gene products of argB and argC.

Aldehyde Oxidoreductases↗