Baker Edward N, Squire Christopher J, Young Paul G
Maurice Wilkins Centre and School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
Maurice Wilkins Centre and School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
Biochem Soc Trans. 2015 Oct;43(5):787-94. doi: 10.1042/BST20150066.
The ability of bacteria to adhere to other cells or to surfaces depends on long, thin adhesive structures that are anchored to their cell walls. These structures include extended protein oligomers known as pili and single, multi-domain polypeptides, mostly based on multiple tandem Ig-like domains. Recent structural studies have revealed the widespread presence of covalent cross-links, not previously seen within proteins, which stabilize these domains. The cross-links discovered so far are either isopeptide bonds that link lysine side chains to the side chains of asparagine or aspartic acid residues or ester bonds between threonine and glutamine side chains. These bonds appear to be formed by spontaneous intramolecular reactions as the proteins fold and are strategically placed so as to impart considerable mechanical strength.
细菌附着于其他细胞或表面的能力取决于附着在其细胞壁上的细长的粘附结构。这些结构包括被称为菌毛的延伸蛋白寡聚体和单个多结构域多肽，大多基于多个串联的免疫球蛋白样结构域。最近的结构研究揭示了共价交联的广泛存在，这在蛋白质中以前未曾见过，它稳定了这些结构域。到目前为止发现的交联要么是将赖氨酸侧链与天冬酰胺或天冬氨酸残基的侧链连接起来的异肽键，要么是苏氨酸和谷氨酰胺侧链之间的酯键。这些键似乎是在蛋白质折叠时由自发的分子内反应形成的，并且其位置经过精心安排，以赋予相当大的机械强度。
