TY - JOUR
T1 - Rhodopsin TM6 can interact with two separate and distinct sites on arrestin
T2 - Evidence for structural plasticity and multiple docking modes in arrestin-rhodopsin binding
AU - Sinha, Abhinav
AU - Jones Brunette, Amber M.
AU - Fay, Jonathan F.
AU - Schafer, Christopher T.
AU - Farrens, David L.
PY - 2014/5/27
Y1 - 2014/5/27
N2 - Various studies have implicated the concave surface of arrestin in the binding of the cytosolic surface of rhodopsin. However, specific sites of contact between the two proteins have not previously been defined in detail. Here, we report that arrestin shares part of the same binding site on rhodopsin as does the transducin Gα subunit C-terminal tail, suggesting binding of both proteins to rhodopsin may share some similar underlying mechanisms. We also identify two areas of contact between the proteins near this region. Both sites lie in the arrestin N-domain, one in the so-called "finger" loop (residues 67-79) and the other in the 160 loop (residues 155-165). We mapped these sites using a novel tryptophan-induced quenching method, in which we introduced Trp residues into arrestin and measured their ability to quench the fluorescence of bimane probes attached to cysteine residues on TM6 of rhodopsin (T242C and T243C). The involvement of finger loop binding to rhodopsin was expected, but the evidence of the arrestin 160 loop contacting rhodopsin was not. Remarkably, our data indicate one site on rhodopsin can interact with multiple structurally separate sites on arrestin that are almost 30 Å apart. Although this observation at first seems paradoxical, in fact, it provides strong support for recent hypotheses that structural plasticity and conformational changes are involved in the arrestin-rhodopsin binding interface and that the two proteins may be able to interact through multiple docking modes, with arrestin binding to both monomeric and dimeric rhodopsin.
AB - Various studies have implicated the concave surface of arrestin in the binding of the cytosolic surface of rhodopsin. However, specific sites of contact between the two proteins have not previously been defined in detail. Here, we report that arrestin shares part of the same binding site on rhodopsin as does the transducin Gα subunit C-terminal tail, suggesting binding of both proteins to rhodopsin may share some similar underlying mechanisms. We also identify two areas of contact between the proteins near this region. Both sites lie in the arrestin N-domain, one in the so-called "finger" loop (residues 67-79) and the other in the 160 loop (residues 155-165). We mapped these sites using a novel tryptophan-induced quenching method, in which we introduced Trp residues into arrestin and measured their ability to quench the fluorescence of bimane probes attached to cysteine residues on TM6 of rhodopsin (T242C and T243C). The involvement of finger loop binding to rhodopsin was expected, but the evidence of the arrestin 160 loop contacting rhodopsin was not. Remarkably, our data indicate one site on rhodopsin can interact with multiple structurally separate sites on arrestin that are almost 30 Å apart. Although this observation at first seems paradoxical, in fact, it provides strong support for recent hypotheses that structural plasticity and conformational changes are involved in the arrestin-rhodopsin binding interface and that the two proteins may be able to interact through multiple docking modes, with arrestin binding to both monomeric and dimeric rhodopsin.
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U2 - 10.1021/bi401534y
DO - 10.1021/bi401534y
M3 - Article
C2 - 24724832
AN - SCOPUS:84901472810
SN - 0006-2960
VL - 53
SP - 3294
EP - 3307
JO - Biochemistry
JF - Biochemistry
IS - 20
ER -