@article { ISI:000372064300044,
	title = {Observing cellulose biosynthesis and membrane translocation in crystallo},
	journal = {NATURE},
	volume = {531},
	number = {7594},
	year = {2016},
	month = {MAR 17},
	pages = {329+},
	abstract = {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 {\textquoteleft}finger helix{\textquoteright} that contacts the polymer{\textquoteright}s terminal glucose. Cooperating with BcsA{\textquoteright}s gating loop, the finger helix moves {\textquoteleft}up{\textquoteright} and {\textquoteleft}down{\textquoteright} in response to substrate binding and polymer elongation, respectively, thereby pushing the elongated polymer into BcsA{\textquoteright}s transmembrane channel. This mechanism is validated experimentally by tethering BcsA{\textquoteright}s finger helix, which inhibits polymer translocation but not elongation.},
	issn = {0028-0836},
	doi = {10.1038/nature16966},
	author = {Morgan, Jacob L. W. and McNamara, Joshua T. and Fischer, Michael and Rich, Jamie and Chen, Hong-Ming and Withers, Stephen G. and Zimmer, Jochen}
}
