학술논문
De novo design of proteins housing excitonically coupled chlorophyll special pairs
Document Type
article
Author
Ennist, Nathan M; Wang, Shunzhi; Kennedy, Madison A; Curti, Mariano; Sutherland, George A; Vasilev, Cvetelin; Redler, Rachel L; Maffeis, Valentin; Shareef, Saeed; Sica, Anthony V; Hua, Ash Sueh; Deshmukh, Arundhati P; Moyer, Adam P; Hicks, Derrick R; Swartz, Avi Z; Cacho, Ralph A; Novy, Nathan; Bera, Asim K; Kang, Alex; Sankaran, Banumathi; Johnson, Matthew P; Phadkule, Amala; Reppert, Mike; Ekiert, Damian; Bhabha, Gira; Stewart, Lance; Caram, Justin R; Stoddard, Barry L; Romero, Elisabet; Hunter, C Neil; Baker, David
Source
Nature Chemical Biology. 20(7)
Subject
Language
Abstract
Natural photosystems couple light harvesting to charge separation using a 'special pair' of chlorophyll molecules that accepts excitation energy from the antenna and initiates an electron-transfer cascade. To investigate the photophysics of special pairs independently of the complexities of native photosynthetic proteins, and as a first step toward creating synthetic photosystems for new energy conversion technologies, we designed C2-symmetric proteins that hold two chlorophyll molecules in closely juxtaposed arrangements. X-ray crystallography confirmed that one designed protein binds two chlorophylls in the same orientation as native special pairs, whereas a second designed protein positions them in a previously unseen geometry. Spectroscopy revealed that the chlorophylls are excitonically coupled, and fluorescence lifetime imaging demonstrated energy transfer. The cryo-electron microscopy structure of a designed 24-chlorophyll octahedral nanocage with a special pair on each edge closely matched the design model. The results suggest that the de novo design of artificial photosynthetic systems is within reach of current computational methods.