9B87

Tetrameric cryo-EM structure of E. coli BcsZ

9B87 の概要

• エントリーDOI: 10.2210/pdb9b87/pdb
• EMDBエントリー: 44334
• 分子名称: Endoglucanase (1 entity in total)
• 機能のキーワード: cellulase, endoglucanase, gh-8 family, carbohydrate-active enzyme, hydrolase
• 由来する生物種: Escherichia coli
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 162923.05

構造登録者

Verma, P.,Zimmer, J. (登録日: 2024-03-29, 公開日: 2025-02-19, 最終更新日: 2025-05-28)

主引用文献

Verma, P.,Ho, R.,Chambers, S.A.,Cegelski, L.,Zimmer, J.
Insights into phosphoethanolamine cellulose synthesis and secretion across the Gram-negative cell envelope.
Nat Commun, 15:7798-7798, 2024

PubMed Abstract: Phosphoethanolamine (pEtN) cellulose is a naturally occurring modified cellulose produced by several Enterobacteriaceae. The minimal components of the E. coli cellulose synthase complex include the catalytically active BcsA enzyme, a hexameric semicircle of the periplasmic BcsB protein, and the outer membrane (OM)-integrated BcsC subunit containing periplasmic tetratricopeptide repeats (TPR). Additional subunits include BcsG, a membrane-anchored periplasmic pEtN transferase associated with BcsA, and BcsZ, a periplasmic cellulase of unknown biological function. While cellulose synthesis and translocation by BcsA are well described, little is known about its pEtN modification and translocation across the cell envelope. We show that the N-terminal cytosolic domain of BcsA positions three BcsG copies near the nascent cellulose polymer. Further, the semicircle's terminal BcsB subunit tethers the N-terminus of a single BcsC protein in a trans-envelope secretion system. BcsC's TPR motifs bind a putative cello-oligosaccharide near the entrance to its OM pore. Additionally, we show that only the hydrolytic activity of BcsZ but not the subunit itself is necessary for cellulose secretion, suggesting a secretion mechanism based on enzymatic removal of translocation incompetent cellulose. Lastly, protein engineering introduces cellulose pEtN modification in orthogonal cellulose biosynthetic systems. These findings advance our understanding of pEtN cellulose modification and secretion.

PubMed: 39242554
DOI: 10.1038/s41467-024-51838-0

実験手法

ELECTRON MICROSCOPY (2.65 Å)