[arg-13 is implicated in mitochondrial ornithine transport in Neurospora crassa].
arg-13 is a leaky mutation involved in arginine metabolism. A tight selection is developed using similar amount of lysine and ornithine replacing other nitrogen source in minimal medium. This selection strongly inhibits the growth of arg-13 under stringent sorbose/glucose condition but allows arg-13 to grow under spot test conditions. As ornithine is build up through mitochondrial ornithine biosynthesis and transport from cytoplasm to mitochondria, arg-13 is combined in genetic crosses with arg-4 which blocks mitochondrial ornithine synthesis. Under spot test conditions, double mutant arg-4, arg-13 is able to use ornithine as sole nitrogen source and arginine biosynthesis precursor, but subject to strong lysine and canavanine inhibition. While the usage of ornithine in arg-4 single mutant with intact ornithine transport function is only slightly inhibited by lysine. All available data suggest arg-13 plays a major role in mitochondrial ornithine transport. The strain carrying the mutation at the arg-13 locus allows inefficient mitochondrial ornithine trafficking, possibly mediated by another distinct basic amino acid carrier.
Liu
Q Y
QY
Biotechnology Research Center, Zhongshan University, Guangzhou 510275, China.
Dunlap
J C
JC
D026905:Amino Acid Transport Systems; D001120:Arginine / Q000494:pharmacology; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000494:pharmacology; D005656:Fungal Proteins / Q000494:pharmacology; D008239:Lysine / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D009492:Neurospora crassa / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D009952:Ornithine / Q000096:biosynthesis* / Q000378:metabolism
D026905:Amino Acid Transport Systems; C103479:Arg-13 protein, Neurospora crassa; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D001120:Arginine; D009952:Ornithine; D008239:Lysine