The crystal structure of red fluorescent protein TagRFP-T reveals the mechanism of its superior photostability.
The red fluorescent protein variant TagRFP-T has greatly improved photostability over its parent molecule, TagRFP, but the underlying mechanism leading to this improvement is to date unknown. The 1.95 Å resolution crystallographic structure of TagRFP-T showed that its chromophore exists as a mixture of cis and trans coplanar isomers in roughly equal proportions. Interestingly, both isomers are able to fluoresce, a property that has never been observed in any other fluorescent protein. We propose a "circular restoration model" for TagRFP-T to explain its superior photostability: There are four co-existing chromophore states (cis/trans protonated/ionized state) that can be driven by light to transform from one state into another. This model also explains how TagRPF-T essentially eliminates the temporary dark state (reversible photobleaching).
Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China.
Rui
R
Liu
Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China.
Qing-Nan
QN
Liang
Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China.
Shu-Qi
SQ
Du
Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China. Electronic address: xjhu@fudan.edu.cn.
Xiao-Jian
XJ
Hu
Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China. Electronic address: yuding@fudan.edu.cn.
Yu
Y
Ding
D003198:Computer Simulation; D003461:Crystallography; D004305:Dose-Response Relationship, Drug; D004355:Drug Stability; D008027:Light; D008164:Luminescent Proteins / Q000737:chemistry / Q000528:radiation effects* / Q000648:ultrastructure*; D008956:Models, Chemical; D008958:Models, Molecular; D011487:Protein Conformation / Q000528:radiation effects*; D011829:Radiation Dosage; D013237:Stereoisomerism; D000097573:Red Fluorescent Protein
D008164:Luminescent Proteins; D000097573:Red Fluorescent Protein
Circular restoration model; Red fluorescent protein; cis and trans conformation