A Novel Mutation within the Kinase Domain of v-abl Gene Responsible for Temperature-Sensitive Colony-Forming Ability in Soft Agar

Abstract

Mutation sites of unique temperature-sensitive (ts) mutants of Abelson murine leukemia virus(A-MuLV) that exhibited the ts phenotype in colony-forming ability in soft agar, but not in morphological transformation, were determined. Cloning and sequencing analysis of the full viral genomes of five independent ts mutants revealed a total of 10 mutation sites: 3 mutations (bp714, 742, and 817) located in the 5′ untranslated region between LTR and gag gene; 4 mutations (bp1227, 1229, 1512, and 1634) in the gag gene; 3 mutations (point mutations at bp2764 and 3265, and 2-base deletion of bp3448 and 3449) in the abl gene. To determine the mutation sites critical for the ts phenotype in colony-forming ability in soft agar, hybrid viruses were constructed by exchanging the corresponding restriction fragments between wild-type and ts A-MuLV. The hybrid virus containing only the point mutation (T → G) at bp 2764 that exchanged leucine with arginine exhibited the ts phenotype in colony-forming ability in soft agar. Thus, a novel mutation within the kinase domain of the abl gone critical for the ts phenotype in colony-forming ability in soft agar was determined here.