title: Interaction of aryl hydrocarbon receptor-interacting protein-like 1 with the farnesyl moiety.
abstract: Aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) is a photoreceptor specific chaperone of the visual effector enzyme phosphodiesterase-6 (PDE6). AIPL1 has been shown to bind the farnesylated PDE6A subunit. Mutations in AIPL1 are thought to destabilize PDE6 and thereby cause Leber congenital amaurosis type 4 (LCA4), a severe form of childhood blindness. Here, we examined the solution structure of AIPL1 by small angle x-ray scattering. A structural model of AIPL1 with the best fit to the scattering data features two independent FK506-binding protein (FKBP)-like and tetratricopeptide repeat domains. Guided by the model, we tested the hypothesis that AIPL1 directly binds the farnesyl moiety. Our studies revealed high affinity binding of the farnesylated-Cys probe to the FKBP-like domain of AIPL1, thus uncovering a novel function of this domain. Mutational analysis of the potential farnesyl-binding sites on AIPL1 identified two critical residues, Cys-89 and Leu-147, located in close proximity in the structure model. The L147A mutation and the LCA-linked C89R mutation prevented the binding of the farnesyl-Cys probe to AIPL1. Furthermore, Cys-89 and Leu-147 flank the unique insert region of AIPL1, deletion of which also abolished the farnesyl interaction. Our results suggest that the binding of PDE6A farnesyl is essential to normal function of AIPL1 and its disruption is one of the mechanisms underlying LCA.
authors.affiliation: From the Department of Molecular Physiology and Biophysics.
authors.forename: Anurima
authors.initials: A
authors.lastname: Majumder
authors.affiliation: From the Department of Molecular Physiology and Biophysics.
authors.forename: Kota N
authors.initials: KN
authors.lastname: Gopalakrishna
authors.affiliation: From the Department of Molecular Physiology and Biophysics.
authors.forename: Pallavi
authors.initials: P
authors.lastname: Cheguru
authors.affiliation: Department of Biochemistry,; Protein Crystallography Facility, and.
authors.forename: Lokesh
authors.initials: L
authors.lastname: Gakhar
authors.affiliation: From the Department of Molecular Physiology and Biophysics,; Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa 52242. Electronic address: nikolai-artemyev@uiowa.edu.
authors.forename: Nikolai O
authors.initials: NO
authors.lastname: Artemyev
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D003545:Cysteine / Q000378:metabolism; D006801:Humans; D057130:Leber Congenital Amaurosis / Q000235:genetics; D051379:Mice; D008958:Models, Molecular; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D054876:Prenylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C498604:Aipl1 protein, mouse; D050505:Mutant Proteins; D003545:Cysteine
keywords: AIPL1; Fluorescence Resonance Energy Transfer (FRET); LCA; Molecular Chaperone; PDE6; Phosphodiesterases; Retinal Degeneration; SAXS; X-ray Scattering