As interest in renewable energy sources has grown, increasing efforts have been focused on utilizing photosynthetic microorganisms for solar energy capture. We use sortase-mediated ligation to attach the photosystem I complex from Synechocystis sp. PCC 6803 in a preferential orientation to enhance the direction of electron flow to a conductive gold surface to convert solar energy into electrical energy. Sortase A is an enzyme found in Gram-postive bacteria that recognizes substrates containing an LPXTG sequence and catalyzes the cleavage of the amide bond between the threonine and the glycine, generating a thioester intermediate. The thioester intermediate undergoes nucleophilic attack by an amino group of an amino-terminated (Gly)3-decorated gold surface. We have engineered subunits of photosystem I to contain the LPXTG-sortase recognition sequence on exposed C-termini for correct orientation for electron transfer. Our current work has shown that using this attachment scheme will produce currents on the hundred nA/cm2 range.

Sortase-mediated ligation of photosystem I from <i>Synechocystis</i> sp. PCC 6803 to a conductive surface for electricity production

245th National Meeting (2013)

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Sortase-mediated ligation of photosystem I from Synechocystis sp. PCC 6803 to a conductive surface for electricity production