Anabaena sensory rhodopsin is a light-driven unidirectional rotor

Angela Strambi , Bo Durbeej , Nicolas Ferré (1) , Massimo Olivucci (2, 3)

1 ICR - Institut de Chimie Radicalaire
2 Dipartimento di Chimica
3 Chemistry Department

The implementation of multiconfigurational quantum chemistry methods into a quantum-mechanics/molecular-mechanics protocol has allowed the construction of a realistic computer model for the sensory rhodopsin of the cyanobacterium Anabaena PCC 7120. The model, which reproduces the absorption spectra of both the all-trans and 13-cis forms of the protein and their associated K and L intermediates, is employed to investigate the light-driven steps of the photochromic cycle exhibited by the protein. It is found that the photoisomerizations of the all-trans and 13-cis retinal chromophores occur through unidirectional, counterclockwise 180 degrees rotations of the =C14-C15= moiety with respect to the Lys210-linked end of the chromophore axis. Thus, the sequential interconversions of the all-trans and 13-cis forms during a single photochromic cycle yield a complete (360 degrees) unidirectional rotation of the =C14-C15= moiety. This finding implies that Anabaena sensory rhodopsin is a biological realization of a light-driven molecular rotor.

Domaines: Chimie

Angela Strambi, Bo Durbeej, Nicolas Ferré, Massimo Olivucci. Anabaena sensory rhodopsin is a light-driven unidirectional rotor. Proceedings of the National Academy of Sciences of the United States of America, 2010, 107 (50), pp.21322--21326. ⟨10.1073/pnas.1015085107⟩. ⟨hal-01460301⟩