56] Use of λ-unc transducing phages in genetic analysis of H+-ATPase mutants of Escherichia coli

Abstract

Publisher Summary The structural genes coding the subunits of the F 1 F 0 H + -ATPase of Escherichia coli are organized in an operon designated unc . A system for genetic complementation using λ-unc transducing phages is developed. The λ- unc transducing phage is lysogenized in a cell carrying a different unc mutation to generate the heterodiploid cell. A λ-transducing phage carrying any unc mutation can be generated. The series of λ- unc transducing phages can be used to genetically define the mutationally altered unc gene in other E. coli host strains. The λ- unc genetic complementation system defines the gene of the unc operon altered by mutation. The degree of intergenic complementation by heterodiploid unc + alleles in a trans configuration varies with the type of mutation and degree of expression of the unc + allele. Hence, negative complementation tests should be interpreted with caution. A positive genetic complementation response can be used to identify the gene altered by mutation and genes that are normal. The normalcy indicated by growth in the complementation test does not rule out the possibility of secondary mutations that may be insufficient by themselves in generating a succinate-minus phenotype.