PLEIOTROPY OF HIST MUTANTS BLOCKED IN PSEUDOURIDINE SYNTHESIS IN TRANSFER-RNA - LEUCINE AND ISOLEUCINE-VALINE OPERONS
PLEIOTROPY OF HIST MUTANTS BLOCKED IN PSEUDOURIDINE SYNTHESIS IN TRANSFER-RNA - LEUCINE AND ISOLEUCINE-VALINE OPERONS
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DOI：
10.1073/pnas.71.5.1857
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发表时间：
1974-01-01
影响因子：
11.1
通讯作者：
AMES, BN
中科院分区：
文献类型：
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作者：
CORTESE, R;LANDSBER.R;AMES, BN
鼠伤寒沙门氏菌的组氨酸基因编码一种酶，在许多种tRNA的反密码子区域负责尿苷转化为假尿苷（pseudouridine，pD）。我们以前已经证明，ahisT突变体的tRNAHis在该区域缺乏假尿苷，因此具有改变的色谱行为。我们在这里显示了所有tRNALeu和一个tRNAIle种的色谱行为的相似改变。相比之下，tRNAVal，除了在T β CG序列中的一个外，不含假尿苷，在ahisTmutant中在色谱上是不变的。我们在这里表明，inhisTmutants的亮氨酸和异亮氨酸和缬氨酸操纵子的调节也受到影响：这些操纵子的酶是难治性的抑制支链氨基酸。然而，在由异亮氨酸或缬氨酸限制引起的去阻遏模式上，hisT和野生型之间没有差异，在基本培养基上生长的细胞中的酶水平只有轻微差异。支链氨基酸操纵子调节的改变也可以解释为什么hisT突变体对氨基酸类似物5，5，5-三氟亮氨酸，β-羟基亮氨酸，和正亮氨酸以及寡肽甘氨酰甘氨酰正亮氨酸和正亮氨酰正亮氨酸。
ThehisTgene codes for an enzyme responsible for the conversion of uridine to pseudouridine (Ψ) in the anticodon region of many tRNA species inSalmonella typhimurium. We have previously shown that ahisTmutant has tRNAHiswhich lacks pseudouridine in this region and as a consequence has an altered chromatographic behavior. We show here a similar alteration in chromatographic behavior of all tRNALeuand one tRNAIlespecies from ahisTmutant. By contrast, tRNAVal, which contains no pseudouridine except for the one in the TΨCG sequence, is chromatographically unaltered in ahisTmutant.The absence of pseudouridine in the anticodon region of tRNA inhisTmutants has been previously shown to cause derepression of the histidine operon. We show here that inhisTmutants the regulation of the leucine and the isoleucine and valine operons is also affected: the enzymes of these operons are refractory to repression by the branched chain amino acids. However, there is no difference betweenhisTand wild type in the pattern of derepression caused by isoleucine or valine limitation and only a slight difference in the enzyme levels in cells grown on minimal medium.The alteration in the regulation of branched chain amino acid operons may also explain whyhisTmutants are resistant to inhibition of growth by the amino acid analogues 5,5,5-trifluoroleucine, β-hydroxyleucine, and norleucine and by the oligopeptides glycylglycylnorleucine and norleucylnorleucine.