Outer membrane mutation effects on UDP–glucose permeability and whole-cell catalysis rate

CARB 51

Ye Ni, niy@vcu.edu, Department of Chemical Engineering, Virginia Commonwealth University, 601 W. Main Street, Box 843028, Richmond, VA 23284 and Rachel R Chen, rchen@chbe.gatech.edu, School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0100.
The reaction catalyzed by the whole-cells is often orders of magnitude slower than that of their isolated enzyme counterparts due to the formidable barrier imposed by cell envelopes. The present research addresses this critical issue by investigating the effects of outer membrane mutation on UDP-glucose utilizing enzymes in whole-cell systems. Owing to the severe limitation in substrate permeability, the wild type cells only exhibited as low as 4% of available enzyme activities. Reducing the barriers of the outer membrane permeability led to a striking acceleration (up to 14 fold) of reaction rate in cells expressing UDP-glucose dehydrogenase. An application of outer membrane mutants in the synthesis of a disaccharide (N-Acetyllactosamine) from UDP-glucose showed that both reaction rate and product yield were enhanced significantly (more than two fold) in the lipoprotein mutant. This research and the results outlined here point to a valid strategy in addressing permeability issues in whole-cell biocatalysis.
 

General Posters
6:00 PM-8:00 PM, Tuesday, 28 March 2006 Georgia World Congress Center -- Ex. Hall B4, Poster

Division of Carbohydrate Chemistry

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006