Hoess R H, Fan D P
J Bacteriol. 1975 Nov;124(2):650-60. doi: 10.1128/jb.124.2.650-660.1975.
The properties of mutR, a mutator closely linked to thyA, have been further characterized. We have found that the mutator gene is carried on a specialized transducing phage (lambdapcI857 thyA) generated by the excision of lambdacI857 integrated at a secondary attachment site between lysA and thyA. We present three lines of evidence indicating that mutR is a nonessential gene. (i) Deletions of the mutator can be found amoung survivors of heat induction of lambdacI857 when the phage is integrated between lysA and thyA. (ii) Mutations in mutR can be induced with the frameshift mutagen ICR-191. (iii) An amber mutant in mutR has been found. Viable strains could be made by combining the mutator with polB, polA polR, ligts7, and uvrA mutations. The mutator was still able to increase the spontaneous mutation frequency in these genetic backgrounds. When the reversion patterns of a series of well-characterized trpA mutations were analyzed, the results suggested that mutR is more efficient at causing transitions than transversion mutations.
与thyA紧密连锁的突变基因mutR的特性已得到进一步表征。我们发现，该突变基因由整合在lysA和thyA之间二级附着位点的λcI857切除产生的一种特殊转导噬菌体（λpcI857 thyA）携带。我们提供了三条证据表明mutR是一个非必需基因。（i）当噬菌体整合在lysA和thyA之间时，在λcI857热诱导的存活菌中可发现突变基因的缺失。（ii）移码诱变剂ICR - 191可诱导mutR发生突变。（iii）已发现mutR中的一个琥珀突变体。通过将突变基因与polB、polA polR、ligts7和uvrA突变相结合可构建出有活力的菌株。在这些遗传背景下，突变基因仍能够提高自发突变频率。当分析一系列特征明确的trpA突变的回复模式时，结果表明mutR在引起转换突变方面比颠换突变更有效。
