Crist Colin G, Kurahashi Hiroshi, Nakayashiki Toru, Nakamura Yoshikazu
Department of Basic Medical Sciences, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Tokyo 108-8639, Japan.
Biochimie. 2006 May;88(5):485-96. doi: 10.1016/j.biochi.2005.10.008. Epub 2005 Nov 8.
The cytoplasmic [PSI(+)] element of budding yeast represents the prion conformation of translation release factor Sup35. Much interest lies in understanding how prions are able to generate variation in isogenic strains. Recent observations suggest that a single prion domain, PrD, is able to adopt several conformations that account for prion strains. We report novel PrD variants of Sup35 that convert weak [PSI(+)] to strong [PSI(+)], and vice versa, upon transmission from wild-type Sup35. During the transmission from wild-type Sup35 to variant Sup35s, no conformational changes were detected by proteolytic fingerprinting and the original [PSI(+)] strain was remembered upon return to wild-type Sup35. These findings suggest that during transmission to variant Sup35s, the [PSI(+)] phenotype is variable while the original conformation is remembered. A mechanism of "conformational memory" to remember specific [PSI(+)] conformations during transmission is proposed.
芽殖酵母的细胞质[PSI(+)]元件代表翻译释放因子Sup35的朊病毒构象。人们对了解朊病毒如何在同基因菌株中产生变异非常感兴趣。最近的观察表明，单个朊病毒结构域PrD能够采用几种构象，这些构象构成了朊病毒菌株。我们报告了Sup35的新型PrD变体，它们在从野生型Sup35传播时会将弱[PSI(+)]转化为强[PSI(+)]，反之亦然。在从野生型Sup35传播到变体Sup35s的过程中，通过蛋白水解指纹图谱未检测到构象变化，并且在恢复到野生型Sup35时，原始的[PSI(+)]菌株得以保留。这些发现表明，在传播到变体Sup35s的过程中，[PSI(+)]表型是可变的，而原始构象被保留。我们提出了一种“构象记忆”机制，以在传播过程中记住特定的[PSI(+)]构象。
