INFLUENCE OF MODIFICATION NEXT TO THE ANTICODON IN TRANSFER-RNA ON CODON CONTEXT-SENSITIVITY OF TRANSLATIONAL SUPPRESSION AND ACCURACY
INFLUENCE OF MODIFICATION NEXT TO THE ANTICODON IN TRANSFER-RNA ON CODON CONTEXT-SENSITIVITY OF TRANSLATIONAL SUPPRESSION AND ACCURACY
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DOI：
10.1128/jb.166.3.1022-1027.1986
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发表时间：
1986-06-01
影响因子：
3.2
通讯作者：
BJORK, GR
中科院分区：
文献类型：
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作者：
BOUADLOUN, F;SRICHAIYO, T;BJORK, GR
研究了突变菌株tRNA中2-甲基硫代- n6 -异戊烯基腺苷（ms2i6A）（大肠杆菌）或2-甲基硫代- n6 -（4-羟基异戊烯基）腺苷（ms2106A）（鼠伤寒沙门氏菌）修饰缺陷对体内翻译的影响。这些超修饰的核苷存在于反密码子的3'侧（位置37），在tRNA读取密码子以尿苷开始。在大肠杆菌中，当色氨酸密码子（UGG）在特定密码子上下文中被第三位误读时，tRNA引起的翻译错误会大大减少，但当精氨酸密码子（CGU）在另一个密码子上下文中被第一位误读时，tRNA引起的翻译错误不会受到影响。UGA无义密码子在两个不同位置的误读依赖于密码子上下文。一些tRNA无义抑制子的效率以tRNA依赖的方式降低。缺少ms2i6A-ms2106A的抑制tRNA对密码子上下文更加敏感。因此，我们的研究结果表明，除了提高翻译效率外，tRNA中的ms2i6A和ms2106A37修饰也参与了降低tRNA固有密码子读取上下文敏感性的过程。对基因表达调控的可能后果进行了讨论。
Effects on translation in vivo by modification deficiencies for 2-methylthio-N6-isopentenyladenosine (ms2i6A) (Escherichia coli) or 2-methylthio-N6-(4-hydroxyisopentenyl)adenosine (ms2106A) (Salmonella typhimurium) in tRNA were studied in mutant strains. These hypermodified nucleosides are present on the 3'' side of the anticodon (position 37) in tRNA reading codons starting with uridine. In E. coli, translational error caused by tRNA was strongly reduced in the case of third-position misreading of a tryptophan codon (UGG) in a particular codon context but was not affected in the case of first-position misreading of an arginine codon (CGU) in another codon context. Misreading of UGA nonsense codons at two different positions was codon context dependent. The efficiencies of some tRNA nonsense suppressors were decreased in a tRNA-dependent manner. Suppressor tRNA which lacks ms2i6A-ms2106A becomes more sensitive to codon context. Our results therefore indicate that, besides improving translational efficiency, ms2i6A and ms2106A37 modifications in tRNA are also involved in decreasing the intrinsic codon reading context sensitivity of tRNA. Possible consequences for regulation of gene expression are discussed.