Absence of clustering of functionally related genes inPseudomonas aeruginosa

Abstract

Phage F116 transduces sufficiently large fragments of thePseudomonas aeruginosachromosome for co-transduction of linked markers to occur. The linkage relationships of 176 auxotrophic mutants have been examined by means of this technique, following characterization of the mutants for their nutritional requirements and by other biochemical means. Thirty-two different loci from fourteen biosynthetic pathways have been differentiated by such combined means. Unlike other bacteria, the clustering of related loci of a biosynthetic pathway appears to be rare. This situation was confirmed for the leucine, methionine, adenine, isoleucine plus valine and arginine pathways. No evidence for linkage of markers within the histidine, proline, cysteine and uracil pathways has been found but further data is needed to completely confirm this conclusion for these groups of markers. The importance of these findings in relation to the genetic control of enzyme biosynthesis in P.aeruginosais discussed. For markers of the tryptophan pathway, two are possibly linked but the other three are definitely not linked. The only confirmed linkage of related markers was between a homoserine locus and a threonine locus.