{"584149":{"#nid":"584149","#data":{"type":"event","title":"A molecular description of cellulose biosynthesis","body":[{"value":"\u003Ch3\u003E\u003Cstrong\u003ESchool of Physics Soft Condensed Matter \u0026amp; Physics of Living Systems Seminar: Prof. Jochen Zimmer, University of Virginia\u003C\/strong\u003E\u003C\/h3\u003E\r\n\r\n\u003Cp\u003EUnder certain conditions, essentially all biopolymers, including nucleic acids, proteins and polysaccharides, must be translocated across at least one membrane to reach their final destinations. Cellulose is a linear glucose polymer synthesized and secreted by a membrane-integrated cellulose synthase. We used in crystallo enzymology with the catalytically active bacterial cellulose synthase BcsA\u0026ndash;B complex to obtain structural snapshots of a complete cellulose synthesis 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. Our structural snapshots reveal that BcsA translocates cellulose via a ratcheting mechanism involving a \u0026lsquo;finger helix\u0026rsquo; that contacts the polymer\u0026rsquo;s terminal glucose. Cooperating with BcsA\u0026rsquo;s gating loop, the finger helix moves \u0026lsquo;up\u0026rsquo; and \u0026lsquo;down\u0026rsquo; in response to substrate binding and polymer elongation, respectively, thereby pushing the elongated polymer into BcsA\u0026rsquo;s transmembrane channel. Taken together, our structural and functional analyses reveal how processive membrane integrated glycosyltransferases couple polymer synthesis with translocation.\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"A molecular description of cellulose biosynthesis"}],"uid":"30957","created_gmt":"2016-11-21 20:43:44","changed_gmt":"2017-04-13 21:13:54","author":"Shaun Ashley","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2016-11-29T15:00:00-05:00","event_time_end":"2016-11-29T16:00:00-05:00","event_time_end_last":"2016-11-29T16:00:00-05:00","gmt_time_start":"2016-11-29 20:00:00","gmt_time_end":"2016-11-29 21:00:00","gmt_time_end_last":"2016-11-29 21:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"126011","name":"School of Physics"}],"categories":[],"keywords":[{"id":"166937","name":"School of Physics"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1795","name":"Seminar\/Lecture\/Colloquium"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"78751","name":"Undergraduate students"},{"id":"174045","name":"Graduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003Eshaun.ashley@physics.gatech.edu\u003C\/p\u003E\r\n","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}