Senger B, Fasiolo F
CNRS, UPR 9002, Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France.
Biochimie. 1996;78(7):597-604. doi: 10.1016/s0300-9084(96)80006-x.
The primordial role of the CAU anticodon in methionine identity of the tRNA has been established by others nearly a decade ago in Escherichia coli and yeast tRNA(Met). We show here that the CAU triplet alone is unable to confer methionine acceptance to a tRNA. This requires the contribution of the discriminatory base A73 and the non-anticodon bases of the anticodon loop. To better understand the functional communication between the anticodon and the active site, we analysed the binding and aminoacylation of tRNA(Met) based anticodon and acceptor-stem minihelices and of tRNA(Met) chimeras where the central core region of yeast tRNA(Met) is replaced by that of unusual mitochondrial forms lacking either a D-stem or a T-stem. These studies suggest that the high selectivity of the anticodon bases in tRNA(Met) implies the L-conformation of the tRNA and the presence of a D-stem. The importance of a L-structure for recognition of tRNA(Met) was also deduced from mutations of tertiary interactions known to play a general role in tRNA(Met) folding.
近十年前，其他人已在大肠杆菌和酵母tRNA(Met)中证实了CAU反密码子在tRNA甲硫氨酸识别中的原始作用。我们在此表明，仅CAU三联体无法赋予tRNA甲硫氨酸接纳能力。这需要鉴别碱基A73和反密码子环的非反密码子碱基的共同作用。为了更好地理解反密码子与活性位点之间的功能联系，我们分析了基于tRNA(Met)反密码子和受体茎的小螺旋以及tRNA(Met)嵌合体（其中酵母tRNA(Met)的中央核心区域被缺乏D茎或T茎的异常线粒体形式的相应区域所取代）的结合和氨酰化情况。这些研究表明tRNA(Met)中反密码子碱基的高选择性意味着tRNA的L构象以及D茎的存在。tRNA(Met)折叠中起普遍作用的三级相互作用的突变也推断出L结构对tRNA(Met)识别的重要性。
