Yeh L C, Deshmukh M, Woolford J L, Lee J C
Department of Biochemistry, University of Texas Health Science Center at San Antonio 78284, USA.
Biochim Biophys Acta. 1996 Aug 14;1308(2):133-41. doi: 10.1016/0167-4781(96)00085-1.
Contributions of the highly conserved K270 and its neighboring K271 in the C-terminal region of the yeast ribosomal protein L1 to 5S rRNA binding and ribosome assembly were examined by in vivo and in vitro studies on the consequences of 14 substitution mutations. All mutant proteins with a single amino-acid substitution at either position were able to bind 5S rRNA in vitro to an extent comparable to the wild-type. Yeast cells expressing these mutant proteins, except the K270G mutant, grew at nearly normal rates. Mutations of K270 appeared to produce more demonstrable effects than those of K271. The double mutant K270,271G bound RNA poorly and yeast cells expressing the mutant protein grew 30% slower. Double mutants K270,271E and K270,271R were lethal, although the mutant protein was assembled into the 60S ribosomal subunits. The resultant subunits were not stable leading eventually to cell death. The in vitro RNA binding ability of the respective protein was reduced by 60% and 20%. Taken together, the present data identified K270 and K271 as important amino-acid residues in the function of the yeast ribosomal protein L1.
通过对14个替代突变后果的体内和体外研究，考察了酵母核糖体蛋白L1 C末端区域高度保守的K270及其相邻的K271对5S rRNA结合和核糖体组装的贡献。在这两个位置上有单个氨基酸替代的所有突变蛋白在体外均能结合5S rRNA，其程度与野生型相当。表达这些突变蛋白的酵母细胞，除了K270G突变体，生长速率接近正常。K270的突变似乎比K271的突变产生更明显的影响。双突变体K270,271G与RNA的结合能力很差，表达该突变蛋白的酵母细胞生长速度慢30%。双突变体K270,271E和K270,271R是致死性的，尽管突变蛋白组装到了60S核糖体亚基中。产生的亚基不稳定，最终导致细胞死亡。相应蛋白的体外RNA结合能力分别降低了60%和20%。综上所述，目前的数据确定K270和K271是酵母核糖体蛋白L1功能中的重要氨基酸残基。
