Cosson Bertrand, Couturier Anne, Chabelskaya Svetlana, Kiktev Denis, Inge-Vechtomov Sergey, Philippe Michel, Zhouravleva Galina
Universite de Rennes 1, CNRS UMR 6061, 35043 Rennes Cedex, France.
Mol Cell Biol. 2002 May;22(10):3301-15. doi: 10.1128/MCB.22.10.3301-3315.2002.
Recent studies of translational control suggest that translation termination may not be simply the end of synthesizing a protein but rather be involved in modulating both the translation efficiency and stability of a given transcript. Using recombinant eukaryotic release factor 3 (eRF3) and cellular extracts, we have shown for Saccharomyces cerevisiae that yeast eRF3 and Pab1p can interact. This interaction, mediated by the N+M domain of eRF3 and amino acids 473 to 577 of Pab1p, was demonstrated to be direct by the two-hybrid approach. We confirmed that a genetic interaction exists between eRF3 and Pab1p and showed that Pab1p overexpression enhances the efficiency of termination in SUP35 (eRF3) mutant and [PSI(+)] cells. This effect requires the interaction of Pab1p with eRF3. These data further strengthen the possibility that Pab1p has a role in coupling translation termination events with initiation of translation. Several lines of evidence indicate that Pab1p does not influence [PSI(+)] propagation. First, "[PSI(+)]-no-more" mutations do not affect eRF3-Pab1p two-hybrid interaction. Second, overexpression of PAB1 does not cure the [PSI(+)] phenotype or solubilize detectable amounts of eRF3. Third, prion-curing properties of overexpressed HSP104p, which is required for formation and maintenance of [PSI(+)], were not modified by excess Pab1p.
近期关于翻译控制的研究表明，翻译终止可能并非仅仅是蛋白质合成的结束，而是参与调节特定转录本的翻译效率和稳定性。利用重组真核释放因子3（eRF3）和细胞提取物，我们已证明酿酒酵母中的酵母eRF3和Pab1p能够相互作用。通过双杂交方法证实，这种由eRF3的N + M结构域与Pab1p的473至577位氨基酸介导的相互作用是直接的。我们证实eRF3和Pab1p之间存在遗传相互作用，并表明Pab1p的过表达增强了SUP35（eRF3）突变体和[PSI(+)]细胞中的终止效率。这种效应需要Pab1p与eRF3相互作用。这些数据进一步强化了Pab1p在将翻译终止事件与翻译起始相偶联中发挥作用的可能性。多条证据表明Pab1p不影响[PSI(+)]的传播。首先，“[PSI(+)]-不再”突变不影响eRF3-Pab1p双杂交相互作用。其次，PAB1的过表达不能治愈[PSI(+)]表型或溶解可检测量的eRF3。第三，过量的Pab1p不会改变过表达的HSP104p的朊病毒治愈特性，而HSP104p是[PSI(+)]形成和维持所必需的。
