Efficient surface-display of autotransporter proteins in cyanobacteria

The autotransporter protein antigen 43 from Escherichia coli was recombinantly expressed in the cyanobacterium Synechocystis sp. PCC6803, under the regulation of the green light-inducible promoter PcpcG2. Antigen 43 expression was induced in response to green light, resulting in the constant accumulation of the protein for at least four days. The complete post-translational processing of the antigen 43 protein was confirmed by Western blot analysis. The resulting antigen 43 α chain was essentially all displayed on the cell surface, as confirmed by proteinase K treatment. Although microbial cell-surface-display technology has a wide range of biotechnological applications, this is the first report of an efficient method for the display of recombinant proteins in cyanobacteria.