The essential Gcd10p-Gcd14p nuclear complex is required for 1-methyladenosine modification and maturation of initiator methionyl-tRNA
The essential Gcd10p-Gcd14p nuclear complex is required for 1-methyladenosine modification and maturation of initiator methionyl-tRNA
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DOI：
10.1101/gad.12.23.3650
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发表时间：
1998-12-01
影响因子：
10.5
通讯作者：
Hinnebusch, AG
中科院分区：
文献类型：
--
作者：
Anderson, J;Phan, L;Hinnebusch, AG
Gcd 10 p和Gcd 14 p是启动GCN 4 mRNA的蛋白质合成和翻译抑制所必需的蛋白质。gcd 10突变体的表型受到高拷贝数IMT基因（编码起始甲硫氨酰tRNA（tRNA（i）（Met））或LHP 1（编码人La自身抗原的酵母同源物））的抑制。gcd 10 -504突变导致成熟tRNA（i）（Met）的稳态水平降低，这归因于周转增加而不是前tRNA（i）（Met）合成减少。值得注意的是，GCD 10缺失的致死性被高拷贝数IMT 4抑制，表明其在成熟tRNA（i）（Met）表达中的作用是GCD 10 p的基本功能。gcd 14 -2突变体也显示成熟tRNA（i）（Met）的量减少，但此外，在前tRNA（i）（Met）加工中显示缺陷。发现Gcd 10 p和Gcd 14 p是蛋白复合物的亚基，具有突出的核定位，表明在tRNA（i）（Met）成熟中的直接作用。延伸子和起始tRNA（Met）在RPC-5柱上的色谱行为表明，这两种物质在gcd 10 Delta细胞中发生了结构改变，碱基修饰分析显示，在gcd 10 Delta tRNA中检测不到1-甲基腺苷（m（1）A）。有趣的是，gcd 10和gcd 14突变对延伸子tRNA（Met）的加工或积累没有影响，它也在58位含有m（1）A，这表明在起始物成熟中对这种碱基修饰的独特要求。
Gcd10p and Gcd14p are essential proteins required for the initiation of protein synthesis and translational repression of GCN4 mRNA. The phenotypes of gcd10 mutants were suppressed by high-copy-number IMT genes, encoding initiator methionyl tRNA (tRNA(i)(Met)), or LHP1, encoding the yeast homolog of the human La autoantigen. The gcd10-504 mutation led to a reduction in steady-state levels of mature tRNA(i)(Met), attributable to increased turnover rather than decreased synthesis of pre-tRNA(i)(Met). Remarkably, the lethality of a GCD10 deletion was suppressed by high-copy-number IMT4, indicating that its role in expression of mature tRNA(i)(Met) is the essential function of Gcd10p. A gcd14-2 mutant also showed reduced amounts of mature tRNA(i)(Met), but in addition, displayed a defect in pre-tRNA(i)(Met) processing. Gcd10p and Gcd14p were found to be subunits of a protein complex with prominent nuclear localization, suggesting a direct role in tRNA(i)(Met) maturation. The chromatographic behavior of elongator and initiator tRNA(Met) on a RPC-5 column indicated that both species are altered structurally in gcd10 Delta cells, and analysis of base modifications revealed that 1-methyladenosine (m(1)A) is undetectable in gcd10 Delta tRNA. Interestingly, gcd10 and gcd14 mutations had no effect on processing or accumulation of elongator tRNA(Met), which also contains m(1)A at position 58, suggesting a unique requirement for this base modification in initiator maturation.