Romaniuk P J, Uhlenbeck O C
Biochemistry. 1985 Jul 16;24(15):4239-44. doi: 10.1021/bi00336a064.
R17 coat protein forms a specific complex with a 21-nucleotide RNA hairpin containing the initiation site for the phage replicase gene. The RNA binding activity of the protein is inhibited by prior incubation with 5-bromouridine (BrU). The inactivation occurs with pseudo-first-order kinetics, and the inactive protein is stable to dilution. RNA binding activity of the BrU-inactivated protein is restored upon incubation with dithiothreitol. Inactivation of coat protein by N-ethylmaleimide or p-(chloromercuri)-benzenesulfonate indicates that a cysteine residue is located near the RNA binding site. Since 5-bromodeoxyuridine does not inactivate coat protein, a specific binding event appears to be required before inactivation can occur. Surprisingly, unmodified cytidine nucleotides also inactivate coat protein, with a specificity similar to the modified analogues. These results are discussed with regard to the formation of a transient covalent RNA-protein bond.
R17外壳蛋白与一个包含噬菌体复制酶基因起始位点的21个核苷酸的RNA发夹结构形成特定复合物。该蛋白的RNA结合活性在与5-溴尿苷（BrU）预先孵育后受到抑制。失活以假一级动力学发生，并且失活的蛋白在稀释时稳定。与二硫苏糖醇孵育后，BrU失活蛋白的RNA结合活性得以恢复。N-乙基马来酰亚胺或对（氯汞）苯磺酸盐使外壳蛋白失活表明一个半胱氨酸残基位于RNA结合位点附近。由于5-溴脱氧尿苷不会使外壳蛋白失活，似乎在失活发生之前需要一个特定的结合事件。令人惊讶的是，未修饰的胞苷核苷酸也会使外壳蛋白失活，其特异性与修饰的类似物相似。针对瞬时共价RNA-蛋白键的形成对这些结果进行了讨论。
