Open AccessA Molecular Mechanism for Nonphotochemical Quenching in Cyanobacteria
Author(s) -
Yue Lü,
Haijun Liu,
Rafael G. Saer,
Veronica L. Li,
Hao Zhang,
Liuqing Shi,
Carrie Goodson,
Michael L. Gross,
Robert E. Blankenship
Publication year - 2017
Publication title -
biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.43
H-Index - 253
eISSN - 1520-4995
pISSN - 0006-2960
DOI - 10.1021/acs.biochem.7b00202
Subject(s) - cyanobacteria , mechanism (biology) , quenching (fluorescence) , chemistry , biophysics , photochemistry , biochemistry , biology , physics , fluorescence , bacteria , genetics , optics , quantum mechanics
The cyanobacterial orange carotenoid protein (OCP) protects photosynthetic cyanobacteria from photodamage by dissipating excess excitation energy collected by phycobilisomes (PBS) as heat. Dissociation of the PBS-OCP complex in vivo is facilitated by another protein known as the fluorescence recovery protein (FRP), which primarily exists as a dimeric complex. We used various mass spectrometry (MS)-based techniques to investigate the molecular mechanism of this FRP-mediated process. FRP in the dimeric state (dFRP) retains its high affinity for the C-terminal domain (CTD) of OCP in the red state (OCP r ). Site-directed mutagenesis and native MS suggest the head region on FRP is a candidate to bind OCP. After attachment to the CTD, the conformational changes of dFRP allow it to bridge the two domains, facilitating the reversion of OCP r into the orange state (OCP o ) accompanied by a structural rearrangement of dFRP. Interestingly, we found a mutual response between FRP and OCP; that is, FRP and OCP r destabilize each other, whereas FRP and OCP o stabilize each other. A detailed mechanism of FRP function is proposed on the basis of the experimental results.