Mapping of the <i>nadB</i> Locus Adjacent to a Previously Undescribed Purine Locus in <i>Escherichia coli</i> K-12

Abstract

It is proposed that all mutants blocked in the de novo pathway of nicotinamide adenine dinucleotide biosynthesis be designated nad rather than nic. It is further suggested that mutants blocked in the pyridine nucleotide cycle be designated pnc. The nadB locus and a previously unidentified pur locus are cotransducible. These two loci have been mapped near minute 49 on the standard genetic map of Escherichia coli. The order of genes in that region is purC-guaB-purG-glyA-pur-nadB-tyrA-pheA.