Sanderson Lee E, Uhlenbeck Olke C
Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA.
RNA. 2007 Jun;13(6):835-40. doi: 10.1261/rna.485307. Epub 2007 Apr 20.
Elongation factor Tu (EF-Tu) exhibits significant specificity for the different elongator tRNA bodies in order to offset its variable affinity to the esterified amino acid. Three X-ray cocrystal structures reveal that while most of the contacts with the protein involve the phosphodiester backbone of tRNA, a single hydrogen bond is observed between the Glu390 and the amino group of a guanine in the 51-63 base pair in the T-stem of tRNA. Here we show that the Glu390Ala mutation of Thermus thermophilus EF-Tu selectively destabilizes binding of those tRNAs containing a guanine at either position 51 or 63 and that mutagenesis of the 51-63 base pair in several tRNAs modulates their binding affinities to EF-Tu. A comparison of Escherichia coli tRNA sequences suggests that this specificity mechanism is conserved across the bacterial domain. While this contact is an important specificity determinant, it is clear that others remain to be identified.
延伸因子Tu（EF-Tu）对不同的延伸tRNA主体表现出显著的特异性，以抵消其对酯化氨基酸的可变亲和力。三个X射线共晶体结构表明，虽然与蛋白质的大多数接触涉及tRNA的磷酸二酯主链，但在tRNA的T茎中51-63碱基对的鸟嘌呤氨基与Glu390之间观察到一个氢键。在这里，我们表明嗜热栖热菌EF-Tu的Glu390Ala突变选择性地破坏了那些在51或63位含有鸟嘌呤的tRNA的结合稳定性，并且几种tRNA中51-63碱基对的诱变调节了它们与EF-Tu的结合亲和力。大肠杆菌tRNA序列的比较表明，这种特异性机制在细菌域中是保守的。虽然这种接触是一个重要的特异性决定因素，但显然还有其他因素有待确定。
