Bossi L, Kohno T, Roth J R
Genetics. 1983 Jan;103(1):31-42. doi: 10.1093/genetics/103.1.31.
A new suppressor of +1 frameshift mutations has been isolated in Salmonella typhimurium. This suppressor, sufJ, maps at minute 89 on the Salmonella genetic map between the argH and rpo(rif) loci, closely linked to the gene for the ochre suppressor tyrU(supM). The suppressor mutation is dominant to its wild-type allele, consistent with the suppressor phenotype being caused by an altered tRNA species. The sufJ map position coincides with that of a threonine tRNA(ACC/U) gene; the suppressor has been shown to read the related fourbase codons ACCU, ACCC, ACCA.--The ability of sufJ to correct one particular mutation depends on the presence of a hisT mutation which causes a defect in tRNA modification. This requirement is allele specific, since other frameshift mutations can be corrected by sufJ regardless of the state of the hisT locus.--Strains carrying both a sufJ and a hisT mutation are acutely sensitive to growth inhibition by uracil; the inhibition is reversed by arginine. This behavior is characteristic of strains with mutations affecting the arginine-uracil biosynthetic enzyme carbamyl phosphate synthetase. The combination of two mutations affecting tRNA structure may reduce expression of the structural gene for this enzyme (pyrA).
在鼠伤寒沙门氏菌中分离出一种新的 +1 移码突变抑制子。这种抑制子 sufJ 位于沙门氏菌遗传图谱的 89 分钟处，在精氨酸琥珀酸合成酶基因（argH）和 RNA 聚合酶基因（rpo(rif)）位点之间，与赭石型抑制子 tyrU(supM) 的基因紧密连锁。抑制子突变对其野生型等位基因呈显性，这与抑制子表型是由改变的 tRNA 种类引起的一致。sufJ 的图谱位置与一个苏氨酸 tRNA(ACC/U) 基因的位置重合；已证明该抑制子能识别相关的四碱基密码子 ACCU、ACCC、ACCA。——sufJ 校正某一特定突变的能力取决于 hisT 突变的存在，hisT 突变会导致 tRNA 修饰缺陷。这种需求是等位基因特异性的，因为无论 hisT 位点的状态如何，其他移码突变都可被 sufJ 校正。——同时携带 sufJ 和 hisT 突变的菌株对尿嘧啶引起的生长抑制极为敏感；精氨酸可逆转这种抑制作用。这种行为是影响精氨酸 - 尿嘧啶生物合成酶氨甲酰磷酸合成酶的突变菌株的特征。影响 tRNA 结构的两种突变的组合可能会降低该酶（pyrA）结构基因的表达。
