Most prokaryotic cells are encased in a surface layer (S-layer) consisting of a paracrystalline array of repeating lattice-forming proteins. S-layer proteins populate a vast and diverse sequence space, performing disparate functions in prokaryotic cells, including cellular defense, cell-shape maintenance, and regulation of import and export of materials. This article highlights recent advances in the understanding of S-layer structure and assembly, made possible by rapidly evolving structural and cell biology methods. We underscore shared assembly principles revealed by recent work and discuss a common molecular framework that may be used to understand the structural organization of S-layer proteins across bacteria and archaea.

大多数原核细胞被包裹在由重复晶格形成蛋白的准晶体阵列组成的表面层（S 层）中。S 层蛋白分布在广阔而多样的序列空间中，在原核细胞中执行不同的功能，包括细胞防御、细胞形状维持和材料进出口的调节。本文重点介绍了 S 层结构和组装的最新进展，这得益于快速发展的结构和细胞生物学方法。我们强调了最近工作揭示的共享组装原则，并讨论了一个共同的分子框架，该框架可用于了解跨细菌和古细菌的 S 层蛋白的结构组织。