title: Isolation and properties of selenomethionine-resistant mutants of Neurospora crassa.
abstract: Mutants resistant to selenomethionine were isolated, and their properties studied. Mapping studies indicate that the mutation sites are located near the eth-1(r) locus in linkage group I, about ten map units away from the mating type locus. The sites of new mutation are either allelic to or very close to eth-1(r). They are resistant not only to selenomethionine but also to ethionine, while the ethionine-resistant mutant, eth-1(r), is sensitive to selenomethionine. The selenomethionine-resistant mutants are also temperature-sensitive mutants. However, they can grow at higher temperatures in medium containing 1 M glycerol.-It is very unlikely that the resistance is due to a change in the permeability of the membrane. Aryl sulfatase of se-met(r) mutants is not repressed by a high concentration of methionine (5 mM), although inorganic sulfate (2 mM) still can cause total repression. The gamma-cystathionase levels of the mutants are normal, but the S-adenosylmethionine synthetase levels are only one-tenth of that observed in the wild-type strain. The heat-stability of this enzyme in the mutant is also different from that of the wild-type enzyme suggesting that the mutation might affect the structural gene of S-adenosylmethionine synthetase.
mesh_terms: D001692:Biological Transport; D002463:Cell Membrane Permeability; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D004352:Drug Resistance, Microbial; D005001:Ethionine / Q000494:pharmacology; D005111:Extrachromosomal Inheritance; D005796:Genes; D008040:Genetic Linkage; D006358:Hot Temperature; D006836:Hydro-Lyases / Q000378:metabolism; D012695:L-Serine Dehydratase / Q000378:metabolism; D008025:Ligases / Q000378:metabolism; D008715:Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009154:Mutation; D009491:Neurospora / Q000187:drug effects*; D009492:Neurospora crassa / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D012436:S-Adenosylmethionine
chemical_list: D012436:S-Adenosylmethionine; D008715:Methionine; D006836:Hydro-Lyases; D012695:L-Serine Dehydratase; D008025:Ligases; D005001:Ethionine