Expression and Analysis of Recombinant Gas Vesicle in Halobacterium

Abstract

Halobacterium is an extremophilic microorganism that lives in high concentration of salt. Halobacterium could survive only under high salinity but lyses in freshwater and seawater, due to the difference in osmotic pressure. Therefore, Halobacterium is an organism of interest for expressing recombinant proteins without concerns about ecosystem disturbance by GMO. Gas vesicles are hollow proteins structures that enable the Halobacterial cells float to the surface of the water. In order to study the structure and function of gas vesicle, gene encoding gas vesicle subunits were modified to contain cysteine and hexa-Histidine tags. Gene encoding gas vesicle subunit C was modified to fuse with the lipase to test its potential for applying gas vesicle on the removal of lipid from watery environment. Recombinant gas vesicle genes were expressed in Escherichia coli and Halobacterium. Recombinant proteins of GvpC and GvpC fused lipase are purified in E. coli and their lipase activities were confirmed by various assay. Effects of the mutations on functional gas vesicle formation and their accessibility to cysteine-specific reagents were analyzed.