Poster: Cell walls
Abs #
610: Characterization of a novel class of plant endo-β-1,4-glucanases that contain a cellulose binding domain
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Presenter: |
Catala, Carmen , cc283@cornell.edu |
Authors | Catala, Carmen (A) Urbanowicz, Breeanna R (A) Irwin, Diana (B) Wilson, David B (B) Rose, Jocelyn K (A) | | Affiliations: |
(A): Department of Plant Biology, Cornell University
(B): Department of Molecular Biology and Genetics, Cornell University
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| Web Site: | http://labs.plantbio.cornell.edu/rose/ | |
Plant endo-β-1,4-D-glucanases (EGases, or cellulases) are cell modifying wall enzymes that are predicted to catalyze the hydrolysis of β-1,4-glucan linkages such as those found in cellulose and xyloglucan, however, their substrate in vivo has still not been determined. There is no evidence that plant EGases can degrade crystalline cellulose and this has been attributed to the fact that, until recently, no plant EGases have been identified that contain a cellulose binding domain (CBD). The CBD module present in EGases from microbes facilitates the binding to and subsequent degradation of crystalline cellulose.
We have identified a novel class of plant EGases unique in that their catalytic core is attached to a distinct C-terminal CBD-like domain. Expression analysis of one such EGase gene, TomCel8 from tomato, suggests a role in wall reorganization during both cell expansion and fruit ripening. We are performing a functional analysis of this class of EGases, through both biochemical characterization and analyses of their physiological roles during plant development. The binding properties of the CBD-like domain of TomCel8 have been studied in domain-swapping experiments between TomCel8 and a well-characterized bacterial cellulase. These studies have shown that indeed, the TomCel8 CBD-like domain confers binding to crystalline cellulose.
The entire TomCel8 protein, the catalytic and CBD-like domains alone, have been expressed in Pichia pastoris and these proteins are being used to test the enzymatic activity and substrate specificity of TomCel8. We are also undertaking a functional evaluation of a three-member family of EGases from Arabidopsis that contain the putative CBD.
