Graduate student
Jaime Becnel

The plant cell wall is a complex structure composed in part of cellulose microfibrils interconnected by a network of xyloglucan polymers. In vitro, xyloglucan endotransglycosylases/hydrolases (XTHs) cleave xyloglucan polymers and religate the newly generated reducing ends to other xyloglucan polymers. Although the biochemical activity of XTHs is well defined, the physiological consequences of this activity in vivo remain undetermined.

Previous work has shown that TCH4 of Arabidopsis encodes an XTH, thus TCH4 has the potential to modify an important component of the cell wall. Analysis of the Arabidopsis database reveals an extensive gene family that encodes 33 XTH proteins. (see figure 1.) The predicted proteins share a high degree of identity as well as a conserved motif (DEIDFEFLG) that is identical to the active site of Bacillus β-glucanases and may be necessary for enzymatic function of the XTHs.

I am investigating the functional significance of this gene family through the characterization of primary protein structures, consequences of loss of function and regulation of gene expression.