TY - JOUR
T1 - Molecular architecture of photoreceptor phosphodiesterase elucidated by chemical cross-linking and integrative modeling
AU - Zeng-Elmore, Xiaohui
AU - Gao, Xiong Zhuo
AU - Pellarin, Riccardo
AU - Schneidman-Duhovny, Dina
AU - Zhang, Xiu Jun
AU - Kozacka, Katie A.
AU - Tang, Yang
AU - Sali, Andrej
AU - Chalkley, Robert J.
AU - Cote, Rick H.
AU - Chu, Feixia
N1 - Publisher Copyright:
© 2014 Elsevier Ltd. All rights reserved.
PY - 2014/11/11
Y1 - 2014/11/11
N2 - Photoreceptor phosphodiesterase (PDE6) is the central effector enzyme in visual excitation pathway in rod and cone photoreceptors. Its tight regulation is essential for the speed, sensitivity, recovery and adaptation of visual detection. Although major steps in the PDE6 activation/deactivation pathway have been identified, mechanistic understanding of PDE6 regulation is limited by the lack of knowledge about the molecular organization of the PDE6 holoenzyme (αβγγ). Here, we characterize the PDE6 holoenzyme by integrative structural determination of the PDE6 catalytic dimer (αβ), based primarily on chemical cross-linking and mass spectrometric analysis. Our models built from high-density cross-linking data elucidate a parallel organization of the two catalytic subunits, with juxtaposed α-helical segments within the tandem regulatory GAF domains to provide multiple sites for dimerization. The two catalytic domains exist in an open configuration when compared to the structure of PDE2 in the apo state. Detailed structural elements for differential binding of the γ-subunit to the GAFa domains of the α- and β-subunits are revealed, providing insight into the regulation of the PDE6 activation/deactivation cycle.
AB - Photoreceptor phosphodiesterase (PDE6) is the central effector enzyme in visual excitation pathway in rod and cone photoreceptors. Its tight regulation is essential for the speed, sensitivity, recovery and adaptation of visual detection. Although major steps in the PDE6 activation/deactivation pathway have been identified, mechanistic understanding of PDE6 regulation is limited by the lack of knowledge about the molecular organization of the PDE6 holoenzyme (αβγγ). Here, we characterize the PDE6 holoenzyme by integrative structural determination of the PDE6 catalytic dimer (αβ), based primarily on chemical cross-linking and mass spectrometric analysis. Our models built from high-density cross-linking data elucidate a parallel organization of the two catalytic subunits, with juxtaposed α-helical segments within the tandem regulatory GAF domains to provide multiple sites for dimerization. The two catalytic domains exist in an open configuration when compared to the structure of PDE2 in the apo state. Detailed structural elements for differential binding of the γ-subunit to the GAFa domains of the α- and β-subunits are revealed, providing insight into the regulation of the PDE6 activation/deactivation cycle.
KW - chemical cross-linking
KW - integrative modeling
KW - mass spectrometry
KW - phosphodiesterase 6 (PDE6)
KW - visual transduction
UR - http://www.scopus.com/inward/record.url?scp=84908190461&partnerID=8YFLogxK
U2 - 10.1016/j.jmb.2014.07.033
DO - 10.1016/j.jmb.2014.07.033
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C2 - 25149264
AN - SCOPUS:84908190461
SN - 0022-2836
VL - 426
SP - 3713
EP - 3728
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 22
ER -