Purchase this article with an account.
Pallavi Cheguru, Anurima Majumder, Gopalakrishna Kota, Lokesh Gakhar, Nikolai Artemyev; Analysis of the complex between transducin-α and UNC119 by Small Angle X-ray Scattering (SAXS). Invest. Ophthalmol. Vis. Sci. 2014;55(13):418.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
UNC119 is a protein partner of transducin-α (Gαt) shown to be important for transducin trafficking in rods. We have examined the solution structure of the UNC119/ Gαt complex by SAXS in order to gain insights into the mechanism of transducin trafficking.
UNC119 and myristoylated chimeric Gαt were co-expressed in E. coli. A highly pure UNC119/ Gαt complex with excellent monodispersity was obtained by a three-step chromatographic procedure. SAXS data on the UNC119/ Gαt complex were collected using different exposure times of synchrotron radiation and varying concentrations of the complex. Combined rigid-body/ab initio modeling against the SAXS data was performed using known atomic structures of UNC119 and Gαt.
Analyses of the scattering curves for the protein complex indicated a radius of gyration (Rg) of 34.7 Å and a maximum particle dimension (Dmax) of 117 Å. The model of the UNC119/ Gαt complex with the best fit to the SAXS data indicated rotation and bending of the N-terminal α-helix (αN) of Gαt from its position in the structure of heterotrimeric Gt. This conformation of αN allows a considerably more compact overall conformation of the complex in which the two molecules have additional interactions involving the β3-β4 loop and the α5-helix/C-terminus of Gαt.
The SAXS solution structure of the UNC119/ Gαt complex suggests a novel interface between UNC119 and Gαt. This interface is potentially critical to the ability of UNC119 to solubilize transducin from the membrane and facilitate its trafficking.
This PDF is available to Subscribers Only