Involvement of distinct arrestin-1 elements in binding to different functional forms of rhodopsin

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 3; pp. 942 - 947
• Main Authors: Zhuang, Tiandi, Chen, Qiuyan, Cho, Min-Kyu, Vishnivetskiy, Sergey A., Iverson, Tina M., Gurevich, Vsevolod V., Sanders, Charles R.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 15.01.2013; National Acad Sciences
• Subjects: Arrestin - chemistry; Arrestin - genetics; Arrestin - metabolism; Binding Sites; Biochemistry; Biological Sciences; Drug interactions; Humans; Kinetics; Models, Molecular; Molecules; Multiprotein Complexes - chemistry; Mutagenesis, Insertional; NMR; Nuclear magnetic resonance; Nuclear Magnetic Resonance, Biomolecular; Opsins; Opsins - chemistry; Opsins - metabolism; Phosphorylation; Photochemical Processes; Photoreceptors; Protein Binding; Protein Conformation; Protein Interaction Domains and Motifs; Proteins; Receptors; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Rhodopsin - chemistry; Rhodopsin - metabolism; Titration
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1215176110

Solution NMR spectroscopy of labeled arrestin-1 was used to explore its interactions with dark-state phosphorylated rhodopsin (P-Rh), phosphorylated opsin (P-opsin), unphosphorylated light-activated rhodopsin (Rh*), and phosphorylated light-activated rhodopsin (P-Rh*). Distinct sets of arrestin-1 elements were seen to be engaged by Rh* and inactive P-Rh, which induced conformational changes that differed from those triggered by binding of P-Rh*. Although arrestin-1 affinity for Rh* was seen to be low (K D > 150 μM), its affinity for P-Rh (K D ∼80 μM) was comparable to the concentration of active monomeric arrestin-1 in the outer segment, suggesting that P-Rh generated by high-gain phosphorylation is occupied by arrestin-1 under physiological conditions and will not signal upon photo-activation. Arrestin-1 was seen to bind P-Rh* and P-opsin with fairly high affinity (K D of ∼50 and 800 nM, respectively), implying that arrestin-1 dissociation is triggered only upon P-opsin regeneration with 11- cis -retinal, precluding noise generated by opsin activity. Based on their observed affinity for arrestin-1, P-opsin and inactive P-Rh very likely affect the physiological monomer-dimer-tetramer equilibrium of arrestin-1, and should therefore be taken into account when modeling photoreceptor function. The data also suggested that complex formation with either P-Rh* or P-opsin results in a global transition in the conformation of arrestin-1, possibly to a dynamic molten globule-like structure. We hypothesize that this transition contributes to the mechanism that triggers preferential interactions of several signaling proteins with receptor-activated arrestins.