Relationship of an unstable argG gene to a 5.7-kilobase amplifiable DNA sequence in Streptomyces lividans 66

Abstract

The relationship between an unstable argG gene and a 5.7-kilobase (kb) (Camr) and that together these genes may be located in a silent chromosomal arc.

A combined genetic and physical map of the Streptomyces coelicolor A3(2) chromosome

“…For example, those in S. glaucescens can be 800 kb or more long (11), and in S. ambofaciens, PFGE analysis has revealed deletions of up to 2 Mb of contiguous DNA (57). In S. lividans and S. coelicolor, frequent deletions at least 40 kb long include the argG locus and a determinant of chloramphenicol resistance (8,29); these genes were located, by recombination analysis, near to 3 o'clock in S. lividans (8).…”

Chloramphenicol resistance in Streptomyces: cloning and characterization of a chloramphenicol hydrolase gene from Streptomyces venezuelae

“…141 "C alone or after mixing with authentic 1,3-diacetoxychloramphenicol. and JGlO had an MIC of 20 pg ml-l but strains M417 and M252, both of which had been selected for sensitivity to chloramphenicol (Betzler et al, 1987;Schottel et al, 198 l), failed to grow at drug concentrations above 3 and 6 pg ml-l, respectively.…”

Genome rearrangement and genetic instability in Streptomyces spp

“…Several groups were, however, able to demonstrate a chromosomal location for genes coding for certain unstable traits (6,11,12), including strS and melC from S. glaucescens. Interestingly, in this species the resulting genetic map (20) could not easily be reconciled with subsequently obtained physical linkage data, which clearly showed that the two loci are 350 kb apart (7).…”

“…22,23,28). Additionally, analyses involving DNA surrounding unstable genes demonstrated that extensive flanking sequences were also absent, implicating large chromosomal deletion events in the instabilities (6,7,18). In S. glaucescens, deletions which were responsible for the loss of the unstable genes coding for tyrosinase (melC) and hydroxystreptomycin phosphotransferase (strS) were initially characterized (22,23).…”

“…In many systems, however, amplification apparently takes place in the absence of any obvious selective pressure and, furthermore, is often closely linked to genetic instability (2,3,14,17,20,21,35), being found only in association with unstable mutations. Indeed, it has recently been demonstrated for S. glaucescens (7) and S. lividans (6) that the structural genes of unstable traits are physically linked to the AUDs in the progenitor chromosome and are removed by extensive chromosomal deletions which terminate either adjacent to or in the neighborhood of the ADSs in the corresponding amplified strains (21) (Fig. 1).…”