Living Systems Institute, University of Exeter, Exeter, UK.
Department of Biosciences, Faculty of Health and Life Sciences, Exeter, UK.
Nat Commun. 2024 Jun 14;15(1):5050. doi: 10.1038/s41467-024-45831-w.
Amongst the major types of archaeal filaments, several have been shown to closely resemble bacterial homologues of the Type IV pili (T4P). Within Sulfolobales, member species encode for three types of T4P, namely the archaellum, the UV-inducible pilus system (Ups) and the archaeal adhesive pilus (Aap). Whereas the archaellum functions primarily in swimming motility, and the Ups in UV-induced cell aggregation and DNA-exchange, the Aap plays an important role in adhesion and twitching motility. Here, we present a cryoEM structure of the Aap of the archaeal model organism Sulfolobus acidocaldarius. We identify the component subunit as AapB and find that while its structure follows the canonical T4P blueprint, it adopts three distinct conformations within the pilus. The tri-conformer Aap structure that we describe challenges our current understanding of pilus structure and sheds new light on the principles of twitching motility.
在主要的古菌丝体类型中，有几种被证明与 IV 型菌毛（T4P）的细菌同源物非常相似。在 Sulfolobales 中，成员物种编码三种 T4P，即菌毛、紫外线诱导的菌毛系统（Ups）和古菌黏附菌毛（Aap）。虽然菌毛主要用于游泳运动，而 Ups 用于紫外线诱导的细胞聚集和 DNA 交换，但 Aap 在黏附和抽动运动中起着重要作用。在这里，我们展示了古菌模式生物嗜酸热硫化叶菌的 Aap 的 cryoEM 结构。我们确定了组成亚基为 AapB，并发现尽管其结构遵循典型的 T4P 蓝图，但它在菌毛内采用了三种不同的构象。我们所描述的三构象 Aap 结构挑战了我们对菌毛结构的现有理解，并为抽动运动的原理提供了新的见解。
