6UJE

Crystal structure of the Clostridial cellulose synthase subunit Z (CcsZ) from Clostridioides difficile

6UJE の概要

• エントリーDOI: 10.2210/pdb6uje/pdb
• 分子名称: Endoglucanase, CALCIUM ION (3 entities in total)
• 機能のキーワード: glycosyl, hydrolase, biofilm, cellulose, gh8
• 由来する生物種: Clostridioides difficile
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 38411.31

構造登録者

Scott, W.,Lowrance, B.,Anderson, A.C.,Weadge, J.T. (登録日: 2019-10-03, 公開日: 2020-10-14, 最終更新日: 2023-10-11)

主引用文献

Scott, W.,Lowrance, B.,Anderson, A.C.,Weadge, J.T.
Identification of the Clostridial cellulose synthase and characterization of the cognate glycosyl hydrolase, CcsZ.
Plos One, 15:e0242686-e0242686, 2020

PubMed Abstract: Biofilms are community structures of bacteria enmeshed in a self-produced matrix of exopolysaccharides. The biofilm matrix serves numerous roles, including resilience and persistence, making biofilms a subject of research interest among persistent clinical pathogens of global health importance. Our current understanding of the underlying biochemical pathways responsible for biosynthesis of these exopolysaccharides is largely limited to Gram-negative bacteria. Clostridia are a class of Gram-positive, anaerobic and spore-forming bacteria and include the important human pathogens Clostridium perfringens, Clostridium botulinum and Clostridioides difficile, among numerous others. Several species of Clostridia have been reported to produce a biofilm matrix that contains an acetylated glucan linked to a series of hypothetical genes. Here, we propose a model for the function of these hypothetical genes, which, using homology modelling, we show plausibly encode a synthase complex responsible for polymerization, modification and export of an O-acetylated cellulose exopolysaccharide. Specifically, the cellulose synthase is homologous to that of the known exopolysaccharide synthases in Gram-negative bacteria. The remaining proteins represent a mosaic of evolutionary lineages that differ from the described Gram-negative cellulose exopolysaccharide synthases, but their predicted functions satisfy all criteria required for a functional cellulose synthase operon. Accordingly, we named these hypothetical genes ccsZABHI, for the Clostridial cellulose synthase (Ccs), in keeping with naming conventions for exopolysaccharide synthase subunits and to distinguish it from the Gram-negative Bcs locus with which it shares only a single one-to-one ortholog. To test our model and assess the identity of the exopolysaccharide, we subcloned the putative glycoside hydrolase encoded by ccsZ and solved the X-ray crystal structure of both apo- and product-bound CcsZ, which belongs to glycoside hydrolase family 5 (GH-5). Although not homologous to the Gram-negative cellulose synthase, which instead encodes the structurally distinct BcsZ belonging to GH-8, we show CcsZ displays specificity for cellulosic materials. This specificity of the synthase-associated glycosyl hydrolase validates our proposal that these hypothetical genes are responsible for biosynthesis of a cellulose exopolysaccharide. The data we present here allowed us to propose a model for Clostridial cellulose synthesis and serves as an entry point to an understanding of cellulose biofilm formation among class Clostridia.

PubMed: 33264329
DOI: 10.1371/journal.pone.0242686

実験手法

X-RAY DIFFRACTION (1.75 Å)