Phosphoinositides are a class of phospholipids generated by the action of phosphoinositide kinases with key regulatory functions in eukaryotic cells. Here, we present the atomic structure of phosphatidylinositol 4-kinase type IIα (PI4K IIα), in complex with ATP solved by X-ray crystallography at 2.8 Å resolution. The structure revealed a non-typical kinase fold that could be divided into N- and C-lobes with the ATP binding groove located in between. Surprisingly, a second ATP was found in a lateral hydrophobic pocket of the C-lobe. Molecular simulations and mutagenesis analysis revealed the membrane binding mode and the putative function of the hydrophobic pocket. Taken together, our results suggest a mechanism of PI4K IIα recruitment, regulation, and function at the membrane.

• Klíčová slova
• Monte Carlo simulations, crystal structure, kinase, membrane, phosphatidyl inositol,
• MeSH
• fosfatidylinositoly chemie   metabolismus   MeSH
• fosfotransferasy s alkoholovou skupinou jako akceptorem chemie   metabolismus   ultrastruktura   MeSH
• inositol chemie   MeSH
• konformace proteinů * MeSH
• krystalografie rentgenová * MeSH
• lidé MeSH
• membrány chemie   MeSH
• metoda Monte Carlo MeSH
• signální transdukce MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• vedlejší histokompatibilní antigeny MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fosfatidylinositoly MeSH
• fosfotransferasy s alkoholovou skupinou jako akceptorem MeSH
• inositol MeSH
• phosphatidylinositol phosphate 4-kinase MeSH Prohlížeč
• vedlejší histokompatibilní antigeny MeSH

Specificity of membrane fusion in vesicular trafficking is dependent on proper subcellular distribution of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). Although SNARE complexes are fairly promiscuous in vitro, substantial specificity is achieved in cells owing to the spatial segregation and shielding of SNARE motifs prior to association with cognate Q-SNAREs. In this study, we identified phosphatidylinositol 4-kinase IIα (PI4K2A) as a binding partner of vesicle-associated membrane protein 3 (VAMP3), a small R-SNARE involved in recycling and retrograde transport, and found that the two proteins co-reside on tubulo-vesicular endosomes. PI4K2A knockdown inhibited VAMP3 trafficking to perinuclear membranes and impaired the rate of VAMP3-mediated recycling of the transferrin receptor. Moreover, depletion of PI4K2A significantly decreased association of VAMP3 with its cognate Q-SNARE Vti1a. Although binding of VAMP3 to PI4K2A did not require kinase activity, acute depletion of phosphatidylinositol 4-phosphate (PtdIns4P) on endosomes significantly delayed VAMP3 trafficking. Modulation of SNARE function by phospholipids had previously been proposed based on in vitro studies, and our study provides mechanistic evidence in support of these claims by identifying PI4K2A and PtdIns4P as regulators of an R-SNARE in intact cells.

• Klíčová slova
• PI4K2A, PtdIns4P, SNARE, Sorting, VAMP3, Vesicle fusion,
• MeSH
• buněčná membrána metabolismus   MeSH
• Cercopithecus aethiops MeSH
• COS buňky MeSH
• endozomy metabolismus   MeSH
• fosfotransferasy s alkoholovou skupinou jako akceptorem metabolismus   MeSH
• fúze membrán fyziologie   MeSH
• lidé MeSH
• membránový protein 3 asociovaný s vezikuly metabolismus   MeSH
• proteiny SNARE metabolismus   MeSH
• receptory transferinu metabolismus   MeSH
• transport proteinů fyziologie   MeSH
• vedlejší histokompatibilní antigeny MeSH
• vezikulární transportní proteiny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Intramural MeSH
• Názvy látek
• fosfotransferasy s alkoholovou skupinou jako akceptorem MeSH
• membránový protein 3 asociovaný s vezikuly MeSH
• phosphatidylinositol phosphate 4-kinase MeSH Prohlížeč
• proteiny SNARE MeSH
• receptory transferinu MeSH
• vedlejší histokompatibilní antigeny MeSH
• vezikulární transportní proteiny MeSH