Mutation spectrum analysis of transglutaminase gene in Streptomyces fradiae after irradiation by N~+ ion

Abstract:

A series of mutants of transglutaminase(TGase) gene from Streptomyces fradiae strains were obtained by low energy N⁺ ion beam irradiation, and the irradiation dose response curve was also investigated. Both the wild type and the mutants of TGase were compared by PCR-SSCP, and specific fragments were sequenced. Then the types of TGase gene mutation induced by N⁺ were characterized. The results show that the types of DNA base mutation included the transition, the transversion and the deletion. In all of the 24 bases of mutants, the base replacement occupies about 87.5% of the total mutants with only a small portion of gene deletion (12.5%). Interestingly, the frequency of the base transition (58.3%) is obviously higher than that of the base transversion (29.2%) among the base replacements. The base substitutions induced by N⁺ ion beam irradiation are C→T transition, A→G transition, G→T transversion, C→G transversion. Furthermore, mutations can be induced in all of the four DNA bases by low energy N⁺ ion beam irradiation, and cytosine shows the highest frequency of mutation.