We previously used sortase-mediated ligation to attach the photosystem I (PSI) complex from Synechocystis sp. PCC 6803 in a preferential orientation to enhance the direction of electron flow to a tri-glycine decorated gold surface to convert solar energy into electrical energy via the C-terminus of the psaE subunit, modified to contain a sortase recognition sequence. This system produced modest current densities. While recent work has shown un-oriented multilayers of PSI on conductive surfaces to successfully produce impressive current densities, attempts to create mono/multilayers of oriented PSI have been less so. These attachments suffer from a lack of directionality and recent work has discussed the use of molecular linkers to orient and attach PSI to a surface using a variety of techniques. Here we have attached PSI via the modified C-terminus of the psaA, psaB psaD, psaI, psaL, and psaM subunits using the highly specific sortase reaction to study the influence the predicted protein orientation will have on current densities produced to guide design of PSI multilayers to enhance current production. Our current work has shown that monolayers in orientations where the iron-sulfur clusters of the PSI complex are oriented towards the gold using this attachment scheme will produce currents on the hundred nA/cm2 range while orientations parallel or away from surface will produce minimal to no current.

Linking photosystem I from <i>Synechocystis</i> sp. PCC 6803 to a conductive surface to study the influence of protein orientation on electricity production

247th National Meeting (2014)

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Linking photosystem I from Synechocystis sp. PCC 6803 to a conductive surface to study the influence of protein orientation on electricity production