Influence of Arrestin on the Photodecay of Bovine Rhodopsin

Abstract

Continued activation of the photocycle of the dim-light receptor rhodopsin leads to accumulation of all-trans-retinal in rod outer segments (ROS). This accumulation can damage the photoreceptor cell. For retinal homeostasis, deactivation processes are initiated in which the release of retinal is delayed. One of the processes involves binding of arrestin to rhodopsin. Here, we investigate the interaction of pre-activated truncated bovine visual arrestin (Tr) with rhodopsin in 1,2diheptanoyl-sn-glycero-3-phosphocholine (DHPC) micelles by solution NMR techniques and flash photolysis spectroscopy. Our results show that formation of the rhodopsin-arrestin complex markedly influences partitioning in the decay kinetics of rhodopsin that involves the simultaneous formation of meta II state and meta III state from the meta I state. Binding of Tr leads to an increase of meta III state population and consequently to a ~2-fold slower release of all-transretinal from rhodopsin.

Rhodopsin kinase and arrestin binding control the decay of photoactivated rhodopsin and dark adaptation of mouse rods

“…Previous in vitro work has suggested that recombinant arrestin can stabilize Meta II, block the Meta III formation, or shift the Meta II/III equilibrium toward Meta II and inhibit the overall rate of all-trans retinal release (Sommer and Farrens, 2006). However, other findings instead suggest the stabilization of Meta III by either full-length arrestin (Burns et al, 2006) or its truncated form, Arr Tr , which is similar to physiologically relevant splice variant p44 (Chatterjee et al, 2015). A major caveat of these biochemical experiments is that they were performed with either detergent-solubilized rhodopsin or purified rod outer segment membranes, in which concentrations of added protein components (and the overall metabolic state of the system) are substantially different from those in intact cells.…”