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UNC119 is required for G protein trafficking in sensory neurons

Nature Neuroscience volume 14, pages 874–880 (2011)Cite this article

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Abstract

UNC119 is widely expressed among vertebrates and other phyla. We found that UNC119 recognized the acylated N terminus of the rod photoreceptor transducin α (Tα) subunit and Caenorhabditis elegans G proteins ODR-3 and GPA-13. The crystal structure of human UNC119 at 1.95-Å resolution revealed an immunoglobulin-like β-sandwich fold. Pulldowns and isothermal titration calorimetry revealed a tight interaction between UNC119 and acylated Gα peptides. The structure of co-crystals of UNC119 with an acylated Tα N-terminal peptide at 2.0 Å revealed that the lipid chain is buried deeply into UNC119′s hydrophobic cavity. UNC119 bound Tα-GTP, inhibiting its GTPase activity, thereby providing a stable UNC119–Tα-GTP complex capable of diffusing from the inner segment back to the outer segment after light-induced translocation. UNC119 deletion in both mouse and C. elegans led to G protein mislocalization. Thus, UNC119 is a Gα subunit cofactor essential for G protein trafficking in sensory cilia.

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Figure 1: Crystal structure of human UNC119.
Figure 2: Interaction of UNC119 with Tα polypeptides.
Figure 3: UNC119 is an acyl-binding protein.
Figure 4: The lipid-binding pocket of UNC119.
Figure 5: UNC119 interacts with Tα-GTP and inhibits GTPase activity.
Figure 6: Slow return of transducin to the outer segment after intense light exposure.
Figure 7: Mislocalization of the G proteins ODR-3 and GPA-13 in a C. elegans unc-119(ed3) mutant.

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Acknowledgements

We thank R. Abramowitz and J. Schwanof for access to the X4A beamline at the National Synchrotron Light Source and G. DeTitta of Hauptman Woodward Research Institute for crystallization screening. This work was supported by US National Institutes of Health grants EY08123 (W.B.), EY019298 (W.B.), EY014800-039003 (National Eye Institute core grant), EY10848 (G.I.) and NS034307 (E.M.J.), by the Howard Hughes Medical Institute (E.M.J.), by a grant from the Protein Structure Initiative of the US National Institutes of Health (U54 GM074958), by the University of Utah Macromolecule Crystallography Core Facility, by a Center Grant of the Foundation Fighting Blindness to the University of Utah, and unrestricted grants to the Departments of Ophthalmology at the University of Utah from Research to Prevent Blindness. W.B. is a recipient of a Research to Prevent Blindness Senior Investigator Award.

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  1. Houbin Zhang and Ryan Constantine: These authors contributed equally to this work.

Authors and Affiliations

  1. Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah, USA

    Houbin Zhang, Ryan Constantine, Cecilia D Gerstner & Wolfgang Baehr

  2. Graduate Program in Neuroscience, University of Utah Health Science Center, Salt Lake City, Utah, USA

    Ryan Constantine

  3. Department of Biological Sciences, Northeast Structural Genomics Consortium, Columbia University, New York, New York, USA

    Sergey Vorobiev, Yang Chen, Jayaraman Seetharaman & Liang Tong

  4. Department of Molecular Biology and Biochemistry, Center for Advanced Biotechnology and Medicine, Northeast Structural Genomics Consortium, Rutgers University, Piscataway, New Jersey, USA

    Yuanpeng Janet Huang, Rong Xiao & Gaetano T Montelione

  5. Department of Biology, University of Utah, Salt Lake City, Utah, USA

    M Wayne Davis, Erik M Jorgensen & Wolfgang Baehr

  6. Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA

    George Inana

  7. Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, USA

    Frank G Whitby & Christopher P Hill

  8. Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, USA

    Erik M Jorgensen

  9. Department of Neurobiology and Anatomy, University of Utah Health Science Center, Salt Lake City, Utah, USA

    Wolfgang Baehr

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Contributions

H.Z. generated pulldown/light-induced translocation results and is responsible for C. elegans immunostaining and imaging. R.C. generated ITC results. R.C., F.G.W. and C.P.H. generated human UNC119/acylated Tα-peptide co-crystals and determined the structure. S.V., Y.C., J.S., Y.J.H., R.X., G.T.M. and L.T. determined the unbound human UNC119 structure. R.C., C.D.G. and W.B. isolated ROS membranes, transducin and determined GTPase activity. M.W.D. and E.M.J. generated transgenic C. elegans mutants. G.I. generated the Unc119 knockout mouse. H.Z., R.C., C.P.H., L.T. and W.B. wrote the manuscript.

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Correspondence to Wolfgang Baehr.

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Zhang, H., Constantine, R., Vorobiev, S. et al. UNC119 is required for G protein trafficking in sensory neurons. Nat Neurosci 14, 874–880 (2011). https://doi.org/10.1038/nn.2835

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