5EIY image
Entry Detail
PDB ID:
5EIY
Title:
Bacterial cellulose synthase bound to a substrate analogue
Biological Source:
PDB Version:
Deposition Date:
2015-10-30
Release Date:
2016-03-09
Method Details:
Experimental Method:
Resolution:
2.95 Å
R-Value Free:
0.24
R-Value Work:
0.22
R-Value Observed:
0.22
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Putative cellulose synthase
Chain IDs:A
Chain Length:803
Number of Molecules:1
Biological Source:Rhodobacter sphaeroides (strain ATCC 17023 / 2.4.1 / NCIB 8253 / DSM 158)
Polymer Type:polypeptide(L)
Description:Putative cellulose synthase
Chain IDs:B
Chain Length:729
Number of Molecules:1
Biological Source:Rhodobacter sphaeroides
Polymer Type:polypeptide(L)
Description:poly(unk)
Chain IDs:C (auth: D)
Chain Length:9
Number of Molecules:1
Biological Source:Rhodobacter sphaeroides
Primary Citation
Observing cellulose biosynthesis and membrane translocation in crystallo.
Nature 531 329 334 (2016)
PMID: 26958837 DOI: 10.1038/nature16966

Abstact

Many biopolymers, including polysaccharides, must be translocated across at least one membrane to reach their site of biological function. Cellulose is a linear glucose polymer synthesized and secreted by a membrane-integrated cellulose synthase. Here, in crystallo enzymology with the catalytically active bacterial cellulose synthase BcsA-BcsB complex reveals structural snapshots of a complete cellulose biosynthesis cycle, from substrate binding to polymer translocation. Substrate- and product-bound structures of BcsA provide the basis for substrate recognition and demonstrate the stepwise elongation of cellulose. Furthermore, the structural snapshots show that BcsA translocates cellulose via a ratcheting mechanism involving a 'finger helix' that contacts the polymer's terminal glucose. Cooperating with BcsA's gating loop, the finger helix moves 'up' and 'down' in response to substrate binding and polymer elongation, respectively, thereby pushing the elongated polymer into BcsA's transmembrane channel. This mechanism is validated experimentally by tethering BcsA's finger helix, which inhibits polymer translocation but not elongation.

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Primary Citation of related structures