Nature of the complementation products formed by a complementing mutant of neurospora crassa.
The mutant am-14 produces no active nicotinamide adenine dinucleotide phosphate-linked glutamate dehydrogenase (GDH) and no protein showing immunological cross-reaction with the enzyme. Nevertheless, it shows complementation with several other am mutants in heterokaryons. Active GDH can be extracted from heterokaryons formed from am-14 and other mutants which, by themselves, produce more or less inactive varieties of the enzyme. The enzyme from am-14 + am-3 heterokaryons can be partially separated from am-3 mutant GDH on a diethylaminoethyl cellulose column. It is characterized by abnormally high thermolability and by a capacity for activation by glutamate. By the same procedure as brings about hybridization between mutant GDH proteins, it has been possible to recover enzyme with the properties of pure am-3 GDH from a partially purified am-14 + am-3 GDH preparation which was initially substantially free of unhybridized am-3 enzyme. This is interpreted as evidence that the active complementation product is a hybrid oligomer containing am-3 monomers and also am-14 monomers, the latter being unable to aggregate by themselves. Heterokaryons formed from am-14 and wild type produce GDH of abnormally high thermolability, presumably due to the formation of am-14 + am(+) hybrids.
D000483:Alleles; D002467:Cell Nucleus; D002845:Chromatography; D004586:Electrophoresis; D004589:Electrophoresis, Disc; D005816:Genetic Complementation Test; D005827:Genetics, Microbial; D005969:Glutamate Dehydrogenase / Q000032:analysis / Q000096:biosynthesis; D008967:Molecular Biology; D009154:Mutation; D009491:Neurospora / Q000201:enzymology
D005969:Glutamate Dehydrogenase