Barik Sailen
Mobile, AL, USA.
Bioinform Biol Insights. 2020 Mar 4;14:1177932220906434. doi: 10.1177/1177932220906434. eCollection 2020.
The tricopeptide (amino acid number in the 30s) repeats constitute some of the most common amino acid repeats in proteins of diverse organisms. The most important representatives of this class are the 34-residue and 35-residue repeats, eponymously known as tetratricopeptide repeat (TPR) and pentatricopeptide repeat (PPR), respectively. The unit motif of both consists of a pair of alpha helices. As members of the large, all-helical repeat classes, TPR and PPR share structural similarities, but also play specific roles in protein function. In this study, a comprehensive bioinformatic analysis of the PPR units and the linkers that connect them was conducted. The results suggested the existence of PPR repeats of various formats, as well as smaller, PPR-unrelated repeats. Besides their length, these repeats differed in amino acid arrangements and location of key amino acids. These findings provide a broader and unified perspective of the pentatricopeptide family while raising provocative questions about the assembly and evolution of these domains.
三肽（30多个氨基酸残基）重复序列是多种生物体蛋白质中一些最常见的氨基酸重复序列。这类重复序列最重要的代表分别是由34个残基和35个残基组成的重复序列，分别被称为四肽重复序列（TPR）和五肽重复序列（PPR）。两者的单位基序均由一对α螺旋组成。作为大型全螺旋重复序列家族的成员，TPR和PPR具有结构相似性，但在蛋白质功能中也发挥着特定作用。在本研究中，对PPR单位及其连接的接头进行了全面的生物信息学分析。结果表明存在各种形式的PPR重复序列以及较小的、与PPR无关的重复序列。除了长度不同外，这些重复序列在氨基酸排列和关键氨基酸位置上也存在差异。这些发现为五肽重复序列家族提供了更广泛和统一的视角，同时也引发了关于这些结构域组装和进化的引人深思的问题。
