Bondarev S A, Shirokolobova E D, Trubitsyna N P, Zhuravleva G A
Mol Biol (Mosk). 2014 Mar-Apr;48(2):314-21.
[PSI+] prion is an amyloid isoform of a release factor Sup35p (eRF3). The structure of these protein aggregates remains unclear despite a long term history of prion amyloids investigations. The N-terminal domain of Sup35p (which is responsible for a propagation of prion) shapes superpleated beta-structure, according to modern concepts. Recently we constructed five double mutations within SUP35 sequence encoding the N-terminal prion-forming domain and investigated properties of mutant proteins. Mutations sup35-M1 (YQ46-47KK) and sup35-M2 (QQ61-62KK) lead to [PSI+] prion loss, while other mutant alleles (sup35-M3 QQ70-71KK; sup35-M4 QQ80-81KK; sup35-M5 QQ89-90KK) maintained prion. For the detail analysis of effects of mutant alleles on Sup35p aggregation we characterized propagation and properties of [PSI] prion in yeast strains bearing different mutant allele combinations. The data obtained have refined a supposed organization of beta-sheets forming by different regions of Sup35p prion-forming domain within amyloid. Also we obtained evidences that mutant sup35-M2 and sup35-M4 alleles change structure of prion aggregates. The prion destabilization by these mutations possibly is connected with decrease of heteroaggregate fragmentation by chaperones.
[PSI+] 朊病毒是释放因子Sup35p（eRF3）的一种淀粉样异构体。尽管对朊病毒淀粉样蛋白进行了长期研究，但这些蛋白质聚集体的结构仍不清楚。根据现代概念，Sup35p的N端结构域（负责朊病毒的传播）形成了超折叠β结构。最近，我们在编码N端朊病毒形成结构域的SUP35序列内构建了五个双突变，并研究了突变蛋白的特性。突变体sup35-M1（YQ46-47KK）和sup35-M2（QQ61-62KK）导致[PSI+]朊病毒丢失，而其他突变等位基因（sup35-M3 QQ70-71KK；sup35-M4 QQ80-81KK；sup35-M5 QQ89-90KK）维持朊病毒状态。为了详细分析突变等位基因对Sup35p聚集的影响，我们对携带不同突变等位基因组合的酵母菌株中[PSI]朊病毒的传播和特性进行了表征。所获得的数据完善了关于Sup35p朊病毒形成结构域不同区域在淀粉样蛋白中形成β折叠的推测组织方式。此外，我们获得的证据表明，突变体sup35-M2和sup35-M4等位基因改变了朊病毒聚集体的结构。这些突变导致的朊病毒不稳定可能与伴侣蛋白介导的异源聚集体碎片化减少有关。
