Chernoff Y O, Newnam G P, Liebman S W
Department of Biological Sciences, University of Illinois Molecular Biology Research Facility, Laboratory for Molecular Biology, Chicago 60607, USA.
Proc Natl Acad Sci U S A. 1996 Mar 19;93(6):2517-22. doi: 10.1073/pnas.93.6.2517.
Mutations at position C1054 of 16S rRNA have previously been shown to cause translational suppression in Escherichia coli. To examine the effects of similar mutations in a eukaryote, all three possible base substitutions and a base deletion were generated at the position of Saccharomyces cerevisiae 18S rRNA corresponding to E. coli C1054. In yeast, as in E. coli, both C1054A (rdn-1A) and C1054G (rdn-1G) caused dominant nonsense suppression. Yeast C1054U (rdn-1T) was a recessive antisuppressor, while yeast C1054-delta (rdn-1delta) led to recessive lethality. Both C1054U and two previously described yeast 18S rRNA antisuppressor mutations, G517A (rdn-2) and U912C (rdn-4), inhibited codon-nonspecific suppression caused by mutations in eukaryotic release factors, sup45 and sup35. However, among these only C1054U inhibited UAA-specific suppressions caused by a UAA-decoding mutant tRNA-Gln (SLT3). Our data implicate eukaryotic C1054 in translational termination, thus suggesting that its function is conserved throughout evolution despite the divergence of nearby nucleotide sequences.
16S rRNA第1054位的突变先前已被证明会导致大肠杆菌中的翻译抑制。为了研究真核生物中类似突变的影响，在酿酒酵母18S rRNA中对应于大肠杆菌C1054的位置产生了所有三种可能的碱基替换和一个碱基缺失。在酵母中，与在大肠杆菌中一样，C1054A（rdn-1A）和C1054G（rdn-1G）都导致显性无义抑制。酵母C1054U（rdn-1T）是隐性反抑制子，而酵母C1054-Δ（rdn-1Δ）导致隐性致死。C1054U和两个先前描述的酵母18S rRNA反抑制子突变G517A（rdn-2）和U912C（rdn-4）都抑制了由真核释放因子sup45和sup35中的突变引起的密码子非特异性抑制。然而，在这些突变中，只有C1054U抑制了由UAA解码突变tRNA-Gln（SLT3）引起的UAA特异性抑制。我们的数据表明真核生物的C1054参与翻译终止，因此表明尽管附近核苷酸序列存在差异，但其功能在整个进化过程中是保守的。
