Faculty of Chemistry, University of Warsaw, 02-093, Warsaw, Poland.
Centre of New Technologies, University of Warsaw, 02-097, Warsaw, Poland.
Proc Natl Acad Sci U S A. 2017 Mar 28;114(13):3415-3420. doi: 10.1073/pnas.1615862114. Epub 2017 Mar 9.
Twenty years after their discovery, knots in proteins are now quite well understood. They are believed to be functionally advantageous and provide extra stability to protein chains. In this work, we go one step further and search for links-entangled structures, more complex than knots, which consist of several components. We derive conditions that proteins need to meet to be able to form links. We search through the entire Protein Data Bank and identify several sequentially nonhomologous chains that form a Hopf link and a Solomon link. We relate topological properties of these proteins to their function and stability and show that the link topology is characteristic of eukaryotes only. We also explain how the presence of links affects the folding pathways of proteins. Finally, we define necessary conditions to form Borromean rings in proteins and show that no structure in the Protein Data Bank forms a link of this type.
二十年后的今天，人们对蛋白质中的结有了相当深入的了解。目前认为，这些结具有功能优势，为蛋白质链提供了额外的稳定性。在这项工作中，我们更进一步，寻找比结更为复杂的由多个部分组成的缠结结构。我们推导出了蛋白质能够形成缠结所需满足的条件。我们遍历了整个蛋白质数据库，鉴定出了几个顺序非同源的链，它们形成了一个霍普夫环和一个所罗门环。我们将这些蛋白质的拓扑性质与其功能和稳定性联系起来，并表明这种结构仅存在于真核生物中。我们还解释了缠结的存在如何影响蛋白质的折叠途径。最后，我们定义了在蛋白质中形成博洛米安环的必要条件，并表明蛋白质数据库中没有任何结构形成这种类型的环。
