Wild-type and mutant forms of homoisocitric dehydrogenase in the yeast Saccharomycopsis lipolytica.
Homoisocitric dehydrogenase (EC 1.1.1.155) has been purified 525-fold from the yeast Saccharomycopsis lipolytica with a yield of 25%. The preparation was judged to be homogeneous by electrophoresis under denaturing and non-denaturing conditions and by isoelectric focusing; it consisted of a single protein with molecular weight of 48000. In the presence of homoisocitric acid, a higher molecular weight was observed, suggesting a dimeric structure for the native enzyme. Complementing mutants devoid of homoisocitric dehydrogenase activity mapped at two closely linked loci (lys9 and lys10). Lys10 mutants displayed NAD-reducing activity, whereas lys9 mutants retained some carboxylating activity. Our results are best explained by the assumption that the active enzyme is a dimer of identical subunits involved in successive dehydrogenation and decarboxylation steps.
D000429:Alcohol Oxidoreductases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001203:Ascomycota / Q000201:enzymology*; D004789:Enzyme Activation; D005816:Genetic Complementation Test; D008040:Genetic Linkage; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D009154:Mutation; D012442:Saccharomycopsis / Q000201:enzymology* / Q000235:genetics; D013045:Species Specificity
D046911:Macromolecular Substances; D000429:Alcohol Oxidoreductases; C021368:homoisocitrate dehydrogenase