title: Genetic mapping of a mutation affecting pyridine nucleotide transhydrogenase in Escherichia coli.
abstract: A mutation, pnt-1, causing loss of pyridine nucleotide transhydrogenase activity in Escherichia coli, was mapped by assaying for the enzyme in extracts of recombinant strains produced by conjugation, F-duction, and P1 transduction. The site of this mutation was near min 35, counterclockwise from man, and it co-transduced 59% with man. The mutation was associated with loss from the cell membrane fraction of energy-independent and adenosine 5'-triphosphate-dependent transhydrogenase activities, but reduced nicotinamide adenine dinucleotide dehydrogenase activity was not affected. Strains were constructed which lack phosphoglucoisomerase (pgi-2) and which carry either pnt+ or pnt-1. Although such strains, when grown on glucose, are expected to produce a large excess of reduced nicotinamide adenine dinucleotide phosphate, the growth rate was not affected by the pnt-1 allele.
mesh_terms: D002462:Cell Membrane / Q000201:enzymology; D002874:Chromosome Mapping; D003227:Conjugation, Genetic; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005956:Glucose-6-Phosphate Isomerase / Q000235:genetics; D009154:Mutation; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D009250:NADP Transhydrogenases / Q000235:genetics* / Q000378:metabolism; D014161:Transduction, Genetic
chemical_list: D009247:NADH, NADPH Oxidoreductases; D009250:NADP Transhydrogenases; D005956:Glucose-6-Phosphate Isomerase