Göringer H U, Hijazi K A, Murgola E J, Dahlberg A E
Max-Planck-Institut für Molekulare Genetik, Abteilung Wittmann, Berlin, Federal Republic of Germany.
Proc Natl Acad Sci U S A. 1991 Aug 1;88(15):6603-7. doi: 10.1073/pnas.88.15.6603.
Site-directed mutagenesis was performed on a sequence motif within the 3' major domain of Escherichia coli 16S rRNA shown previously to be important for peptide chain termination. Analysis of stop codon suppression by the various mutants showed an exclusive response to UGA stop signals, which was correlated directly with the continuity of one or the other of two tandem complementary UCA sequences (bases 1199-1204). Since no other structural features of the mutated ribosomes were hampered and the translation initiation and elongation events functioned properly, we propose that a direct interaction occurs between the UGA stop codon on the mRNA and the 16S rRNA UCA motif as one of the initial events of UGA-dependent peptide chain termination. These results provide evidence that base pairing between rRNA and mRNA plays a direct role in termination, as it has already been shown to do for initiation and elongation.
对大肠杆菌16S rRNA 3' 主要结构域内的一个序列基序进行了定点诱变，该序列基序先前已被证明对肽链终止很重要。对各种突变体的终止密码子抑制分析表明，它们对UGA终止信号有唯一反应，这与两个串联互补UCA序列（碱基1199 - 1204）中一个或另一个的连续性直接相关。由于突变核糖体的其他结构特征未受影响，且翻译起始和延伸过程正常运作，我们提出mRNA上的UGA终止密码子与16S rRNA UCA基序之间发生直接相互作用，这是依赖UGA的肽链终止的初始事件之一。这些结果提供了证据，表明rRNA与mRNA之间的碱基配对在终止过程中起直接作用，正如它在起始和延伸过程中所起的作用一样。
