School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur-721302, West Bengal, India.
FEMS Microbiol Lett. 2021 Feb 4;368(2). doi: 10.1093/femsle/fnaa220.
Immunoglobulin (Ig) domains are one of the most widespread protein domains encoded by the human genome and are present in a large array of proteins with diverse biological functions. These Ig domains possess a central structure, the immunoglobulin-fold, which is a sandwich of two β sheets, each made up of anti-parallel β strands, surrounding a central hydrophobic core. Apart from humans, proteins containing Ig-like domains are also distributed in a vast selection of organisms including vertebrates, invertebrates, plants, viruses and bacteria where they execute a wide array of discrete cellular functions. In this review, we have described the key structural deviations of bacterial Ig-folds when compared to the classical eukaryotic Ig-fold. Further, we have comprehensively grouped all the Ig-domain containing adhesins present in both Gram-negative and Gram-positive bacteria. Additionally, we describe the role of these particular adhesins in host tissue attachment, colonization and subsequent infection by both pathogenic and non-pathogenic Escherichia coli as well as other bacterial species. The structural properties of these Ig-domain containing adhesins, along with their interactions with specific Ig-like and non Ig-like binding partners present on the host cell surface have been discussed in detail.
免疫球蛋白 (Ig) 结构域是人类基因组编码的最广泛的蛋白质结构域之一，存在于具有多种生物学功能的大量蛋白质中。这些 Ig 结构域具有中央结构，即免疫球蛋白折叠，它由两个β片层组成，每个β片层由反平行的β链组成，围绕着一个中央疏水性核心。除了人类，含有 Ig 样结构域的蛋白质还分布在包括脊椎动物、无脊椎动物、植物、病毒和细菌在内的大量生物体中，它们在这些生物体中执行广泛的离散细胞功能。在这篇综述中，我们描述了细菌 Ig 折叠与经典真核 Ig 折叠相比的关键结构偏差。此外，我们全面地将所有存在于革兰氏阴性菌和革兰氏阳性菌中的 Ig 结构域包含的黏附素进行了分组。此外，我们还描述了这些特定黏附素在致病性和非致病性大肠杆菌以及其他细菌物种对宿主组织附着、定植和随后感染中的作用。详细讨论了这些 Ig 结构域包含的黏附素的结构特性，以及它们与宿主细胞表面上特定的 Ig 样和非 Ig 样结合伴侣的相互作用。
