THE SIGNAL FOR THE TERMINATION OF PROTEIN-SYNTHESIS IN PROCARYOTES
THE SIGNAL FOR THE TERMINATION OF PROTEIN-SYNTHESIS IN PROCARYOTES
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DOI：
10.1093/nar/18.8.2079
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发表时间：
1990-04-25
影响因子：
14.9
通讯作者：
TATE, WP
中科院分区：
文献类型：
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作者：
BROWN, CM;STOCKWELL, PA;TATE, WP
862大肠杆菌基因的终止密码子周围的序列进行了分析，以确定任何其他功能，有助于终止蛋白质合成的信号。在终止密码子之前和之后观察到与预期核苷酸分布的高度显著偏差。在E.在大肠杆菌中，偏好NAR形式的密码子（任何碱基、腺嘌呤、嘌呤），特别是编码谷氨酰胺或碱性氨基酸的那些。相反，苏氨酸或支链非极性氨基酸的密码子代表性不足。尿苷在紧接所有三个终止密码子之后的核苷酸位置中过度代表，而腺嘌呤和胞嘧啶则代表不足。这种模式在高表达基因中突出，但在低表达基因或终止于UAG的基因中不明显，UAG是多肽链释放因子-1特异性识别的密码子。这些观察结果表明，为了有效地终止蛋白质合成在E。在大肠杆菌中，“终止信号”可能是四核苷酸，而不是简单的三核苷酸密码子，并且多肽链释放因子-2识别这种延伸的信号。终止密码子之后的序列在来自其他几种原核生物和噬菌体的基因中进行了分析。鼠伤寒沙门氏菌、枯草芽孢杆菌、噬菌体和产甲烷古细菌对大肠杆菌的选择性有相似的偏向性。杆菌
The sequences around the stop codons of 862 Escherichia coli genes have been analysed to identify any additional features which contribute to the signal for the termination of protein synthesis. Highly significant deviations from the expected nucleotide distribution were observed, both before and after the stop codon. Immediately prior to UAA stop codons in E. coli there is a preference for codons of the form NAR (any base, adenine, purine), and in particular those that code for glutamine or the basic amino acids. In contrast, codons for threonine or branched nonpolar amino acids were under-represented. Uridine was over-represented in the nucleotide position immediately following all three stop codons, whereas adenine and cytosine were under-represented. This pattern is accentuated in highly expressed genes, but is not as marked in either lowly expressed genes or those that terminate in UAG, the codon specifically recognised by polypeptide chain release factor-1. These observations suggest that for the efficient termination of protein synthesis in E. coli, the ''stop signal'' may be a tetranucleotide, rather than simply a tri-nucleotide codon, and that polypeptide chain release factor-2 recognises this extended signal. The sequence following stop codons was analysed in genes from several other procaryotes and bacteriophages. Salmonella typhimurium, Bacillus subtilis, bacteriophages and the methanogenic archaebacteria showed a similar bias to E. coli.