Surface Display of Dimeric Sorbitol Dehydrogenase Using BrkA Autotransporter

Abstract

Autodisplay is a technology that enables the display of functional proteins and enzymes on the surface of bacteria using type Va autotransporters for various purposes, including whole-cell biocatalysts. BrkA is an autotransporter found in Bordetella pertussis and has been used to display recombinant proteins on E. coli.  Here, we use BrkA to display sorbitol dehydrogenase (SDH) from Rhodobacter sphaeroides to demonstrate successful dimerization of monomeric subunits. Surface display and dimerization of BrkA-SDH fusion proteins on Escherichia coli was validated through trypsin accessibility assay and Western blot. Minor levels of enzyme activity were observed from surface displayed SDH by monitoring the conversion of NAD+ to NADH in the presence of sorbitol. This study demonstrates the first instance of BrkA autodisplay of dimeric proteins. Broadening this technology to include the display of multimeric or interacting surface proteins is of interest to the design of whole-cell biocatalysts.