Mechanisms of spontaneous mutation in DNA repair-proficient Escherichia coli

摘要: Abstract This paper describes the DNA sequence analysis of 729 independent spontaneous lacI − mutation total is comprised 478 novel mutations and 251 previously described events, therefore should allow a more comprehensive view in Escherichia coli . The spectrum dominated by hotspot (71% all events). Mutations at this site consist related addition deletion events involving number repetitive sequences. Here we discuss how frequency proportion these vary different repair-deficient genetic backgrounds. distribution non-hotspot includes base substitutions (38%), deletions (35%), frameshifts (14%), duplications (4%) insertion elements (4%). G:C → A:T dominate among substitutions, while C:G are least common; remaining types substitution equally represented. Among deletions, significant do not display repeated sequences their endpoints (26/72). However, almost multiply recovered (15/17) possess capable accounting for endpoints. Similarily, over (5/7) Single-base divided between sites, each case (−) 1 occur 3-fold frequently that (+)1 events. A comparative mutational class to spectra available variety repair/metabolism-deficient strains presented here an attempt assess possible contributions from chemical, physical enzymic sources damage.