The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
George M. Carman - One of the best experts on this subject based on the ideXlab platform.
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A WASp-binding type II Phosphatidylinositol 4-kinase required for actin polymerization-driven endosome motility
The Journal of cell biology, 2005Co-Authors: Fanny S. Chang, George M. Carman, Gil-soo Han, Kendall J. BlumerAbstract:Endosomes in yeast have been hypothesized to move through the cytoplasm by the momentum gained after actin polymerization has driven endosome abscision from the plasma membrane. Alternatively, after abscission, ongoing actin polymerization on endosomes could power transport. Here, we tested these hypotheses by showing that the Arp2/3 complex activation domain (WCA) of Las17 (Wiskott-Aldrich syndrome protein [WASp] homologue) fused to an endocytic cargo protein (Ste2) rescued endosome motility in las17ΔWCA mutants, and that capping actin filament barbed ends inhibited endosome motility but not endocytic internalization. Motility therefore requires continual actin polymerization on endosomes. We also explored how Las17 is regulated. Endosome motility required the Las17-binding protein Lsb6, a type II Phosphatidylinositol 4-kinase. Catalytically inactive Lsb6 interacted with Las17 and promoted endosome motility. Lsb6 therefore is a novel regulator of Las17 that mediates endosome motility independent of Phosphatidylinositol 4-phosphate synthesis. Mammalian type II Phosphatidylinositol 4-kinases may regulate WASp proteins and endosome motility.
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Phosphatidylinositol 4-kinases in Saccharomyces cerevisiae
Advances in Lipobiology, 1996Co-Authors: George M. Carman, Rosa J. Buxeda, Joseph T. NickelsAbstract:Abstract Phosphatidylinositol 4-kinase from the yeast Saccharomyces cerevisiae catalyzes the formation of Phosphatidylinositol 4-phosphate and ADP from Phosphatidylinositol and ATP. Phosphatidylinositol 4-kinase catalyzes the first phosphorylation reaction in the reaction sequence Phosphatidylinositol → Phosphatidylinositol 4-phosphate → Phosphatidylinositol 4,5-bisphosphate. This phosphorylation sequence in S. cerevisiae is regulated by glucose and sterol. Phosphatidylinositol 4,5-bisphosphate appears to play an essential role in cell proliferation of S. cerevisiae . Since Phosphatidylinositol 4-kinase catalyzes the first step in the phosphorylation sequence of Phosphatidylinositol, the enzyme should play a major role in phosphoinositide synthesis and cell growth in S. cerevisiae . Two membrane-associated (45 kDa and 55 kDa) forms and one cytosolic-associated (125 kDa) form of Phosphatidylinositol 4-kinase have been purified and characterized from S. cerevisiae . The membrane-associated Phosphatidylinositol 4-kinases differ with respect to their physiochemical, enzymological, and kinetic properties. The binding and catalytic steps of the reactions catalyzed by the membrane-associated Phosphatidylinositol 4-kinases toward Phosphatidylinositol has been been defined through meaningful kinetic analyses using Triton X-100/PI-mixed micelles. Detailed kinetic analyses of the inhibition of membrane-associated Phosphatidylinositol 4-kinases by nucleotides has led to insights on the regulation of phosphoinositide synthesis in response to glucose.
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Purification, characterization, and kinetic analysis of a 55-kDa form of Phosphatidylinositol 4-kinase from Saccharomyces cerevisiae.
The Journal of biological chemistry, 1992Co-Authors: Joseph T. Nickels, Rosa J. Buxeda, George M. CarmanAbstract:Abstract A 55-kDa form of membrane-associated Phosphatidylinositol 4-kinase (ATP:Phosphatidylinositol 4-phosphotransferase, EC 2.7.1.67) was purified 10,166-fold from Saccharomyces cerevisiae. The purification procedure included solubilization of microsome membranes with 1% Triton X-100 followed by chromatography with DE52, hydroxylapatite I, Q-Sepharose, Mono Q, and hydroxylapatite II. The procedure resulted in a nearly homogeneous 55-kDa Phosphatidylinositol 4-kinase preparation. The 55-kDa Phosphatidylinositol 4-kinase and the previously purified 45-kDa Phosphatidylinositol 4-kinase differed with respect to their amino acid composition, isoelectric points, and peptide maps. Furthermore, the two forms of Phosphatidylinositol 4-kinase did not show an immunological relationship. Maximum 55-kDa Phosphatidylinositol 4-kinase activity was dependent on magnesium (10 mM) or manganese (0.5 mM) ions and Triton X-100 at the pH optimum of 7.0. The activation energy for the reaction was 12 kcal/mol, and the enzyme was labile above 30 degrees C. The enzyme was inhibited by thioreactive agents, MgADP, and calcium ions. A detailed kinetic analysis of the purified enzyme was performed using Triton X-100/Phosphatidylinositol-mixed micelles. 55-kDa Phosphatidylinositol 4-kinase activity followed saturation kinetics with respect to the bulk and surface concentrations of Phosphatidylinositol and followed surface dilution kinetics. The interfacial Michaelis constant (Km) and the dissociation constant (Ks) for Phosphatidylinositol in the Triton X-100 micelle surface were 1.3 mol % and 0.035 mM, respectively. The Km for MgATP was 0.36 mM. 55-kDa Phosphatidylinositol 4-kinase catalyzed a sequential reaction mechanism as indicated by the results of kinetic and isotopic exchange reactions. The enzyme bound to Phosphatidylinositol before ATP and released Phosphatidylinositol 4-phosphate before ADP. The enzymological and kinetic properties of the 55-kDa Phosphatidylinositol 4-kinase differed significantly from those of the 45-kDa Phosphatidylinositol 4-kinase. This may suggest that the two forms of Phosphatidylinositol 4-kinase from S. cerevisiae are regulated differentially in vivo.
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Phosphatidylinositol 4-kinase from yeast.
Methods in enzymology, 1992Co-Authors: George M. Carman, Charles J. Belunis, Joseph T. NickelsAbstract:Publisher Summary Phosphatidylinositol 4-kinase (1-Phosphatidylinositol kinase) catalyzes the reaction of Phosphatidylinositol with ATP to form Phosphatidylinositol 4-phosphate. Phosphatidylinositol 4-kinase (ATP:1-phosphatidyl-lD-myo-inositol 4-phosphotransferase) is the first enzyme in the phosphorylation sequence of Phosphatidylinositol leading to the formation of Phosphatidylinositol 4-phosphate and Phosphatidylinositol 4,5-bisphosphate in Saccharomyces cerevisiae (S. cerevisiae). The synthesis and turnover of the polyphosphoinositides in S. cerevisiae and in higher eukaryotes play an important role in cell growth. Phosphatidylinositol 4-kinase is associated with the microsomal, plasma membrane, and cytosolic fractions of S. cerevisiae. Phosphatidylinositol 4-kinase has been purified to near homogeneity from the microsomal fraction of S. cerevisiae by standard protein purification procedures. The chapter describes the purification and properties of the enzyme. The properties of Phosphatidylinositol 4-kinase are also discussed. Pure Phosphatidylinositol 4-kinase can be used to synthesize radiolabeled Phosphatidylinositol 4-phosphate.
Ronald F. Coburn - One of the best experts on this subject based on the ideXlab platform.
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Effects of polyamines and calcium and sodium ions on smooth muscle cytoskeleton-associated Phosphatidylinositol (4)-phosphate 5-kinase.
Journal of Cellular Physiology, 1998Co-Authors: H Chen, Carl B. Baron, T. Griffiths, P. Greeley, Ronald F. CoburnAbstract:: In many different cell types, including smooth muscle cells (Baron et al., 1989, Am. J. Physiol., 256: C375-383; Baron et al., J. Pharmacol. Exp. Ther. 266: 8-15), Phosphatidylinositol (4)-phosphate 5-kinase plays a critical role in the regulation of membrane concentrations of Phosphatidylinositol (4,5)-bisphosphate and formation of inositol (1,4,5)-trisphosphate. In unstimulated porcine trachealis smooth muscle, 70% of total cellular Phosphatidylinositol (4)-phosphate 5-kinase activity was associated with cytoskeletal proteins and only trace activity was detectable in isolated sarcolemma. Using two different preparations, we studied cytoskeleton-associated phosphatidyl inositol (4)-phosphate 5-kinase under conditions that attempted to mimic the ionic and thermal cytoplasmic environment of living cells. The cytoskeleton-associated enzyme, studied using Phosphatidylinositol (4)-phosphate substrate concentrations that produced Phosphatidylinositol 4,5-bisphosphate at about 10% of the maximal rate, was sensitive to free [Mg2+], had an absolute requirement for phosphatidylserine, phosphatidic acid, or Phosphatidylinositol, and included type I isoforms. At 0.5 mM free [Mg2+], physiological spermine concentrations, 0.2-0.4 mM, increased Phosphatidylinositol (4)-phosphate 5-kinase activity two to four times compared to controls run without spermine. The EC50 for spermine-evoked increases in activity was 0.17 +/- 0.02 mM. Spermine-evoked enzyme activity was a function of both free [Mg2+] and substrate concentration. Cytoskeleton-associated Phosphatidylinositol (4)-phosphate 5-kinase was inhibited by free [Ca2+] over a physiological range for cytoplasm--10(-8) to 10(-5) M, an effect independent of the presence of calmodulin. Na+ over the range 20 to 50 mM also inhibited this enzyme activated by 5 mM Mg2+ but had no effect on spermine-activated enzyme. Na+, Ca2+, and spermine appear to be physiological modulators of smooth muscle cytoskeleton-bound Phosphatidylinositol (4)-phosphate 5-kinase.
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Effects of polyamines and calcium and sodium ions on smooth muscle cytoskeleton-associated Phosphatidylinositol (4)-phosphate 5-kinase.
Journal of Cellular Physiology, 1998Co-Authors: H Chen, Carl B. Baron, T. Griffiths, P. Greeley, Ronald F. CoburnAbstract:: In many different cell types, including smooth muscle cells (Baron et al., 1989, Am. J. Physiol., 256: C375-383; Baron et al., J. Pharmacol. Exp. Ther. 266: 8-15), Phosphatidylinositol (4)-phosphate 5-kinase plays a critical role in the regulation of membrane concentrations of Phosphatidylinositol (4,5)-bisphosphate and formation of inositol (1,4,5)-trisphosphate. In unstimulated porcine trachealis smooth muscle, 70% of total cellular Phosphatidylinositol (4)-phosphate 5-kinase activity was associated with cytoskeletal proteins and only trace activity was detectable in isolated sarcolemma. Using two different preparations, we studied cytoskeleton-associated phosphatidyl inositol (4)-phosphate 5-kinase under conditions that attempted to mimic the ionic and thermal cytoplasmic environment of living cells. The cytoskeleton-associated enzyme, studied using Phosphatidylinositol (4)-phosphate substrate concentrations that produced Phosphatidylinositol 4,5-bisphosphate at about 10% of the maximal rate, was sensitive to free [Mg2+], had an absolute requirement for phosphatidylserine, phosphatidic acid, or Phosphatidylinositol, and included type I isoforms. At 0.5 mM free [Mg2+], physiological spermine concentrations, 0.2-0.4 mM, increased Phosphatidylinositol (4)-phosphate 5-kinase activity two to four times compared to controls run without spermine. The EC50 for spermine-evoked increases in activity was 0.17 +/- 0.02 mM. Spermine-evoked enzyme activity was a function of both free [Mg2+] and substrate concentration. Cytoskeleton-associated Phosphatidylinositol (4)-phosphate 5-kinase was inhibited by free [Ca2+] over a physiological range for cytoplasm--10(-8) to 10(-5) M, an effect independent of the presence of calmodulin. Na+ over the range 20 to 50 mM also inhibited this enzyme activated by 5 mM Mg2+ but had no effect on spermine-activated enzyme. Na+, Ca2+, and spermine appear to be physiological modulators of smooth muscle cytoskeleton-bound Phosphatidylinositol (4)-phosphate 5-kinase.
Joseph T. Nickels - One of the best experts on this subject based on the ideXlab platform.
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Phosphatidylinositol 4-kinases in Saccharomyces cerevisiae
Advances in Lipobiology, 1996Co-Authors: George M. Carman, Rosa J. Buxeda, Joseph T. NickelsAbstract:Abstract Phosphatidylinositol 4-kinase from the yeast Saccharomyces cerevisiae catalyzes the formation of Phosphatidylinositol 4-phosphate and ADP from Phosphatidylinositol and ATP. Phosphatidylinositol 4-kinase catalyzes the first phosphorylation reaction in the reaction sequence Phosphatidylinositol → Phosphatidylinositol 4-phosphate → Phosphatidylinositol 4,5-bisphosphate. This phosphorylation sequence in S. cerevisiae is regulated by glucose and sterol. Phosphatidylinositol 4,5-bisphosphate appears to play an essential role in cell proliferation of S. cerevisiae . Since Phosphatidylinositol 4-kinase catalyzes the first step in the phosphorylation sequence of Phosphatidylinositol, the enzyme should play a major role in phosphoinositide synthesis and cell growth in S. cerevisiae . Two membrane-associated (45 kDa and 55 kDa) forms and one cytosolic-associated (125 kDa) form of Phosphatidylinositol 4-kinase have been purified and characterized from S. cerevisiae . The membrane-associated Phosphatidylinositol 4-kinases differ with respect to their physiochemical, enzymological, and kinetic properties. The binding and catalytic steps of the reactions catalyzed by the membrane-associated Phosphatidylinositol 4-kinases toward Phosphatidylinositol has been been defined through meaningful kinetic analyses using Triton X-100/PI-mixed micelles. Detailed kinetic analyses of the inhibition of membrane-associated Phosphatidylinositol 4-kinases by nucleotides has led to insights on the regulation of phosphoinositide synthesis in response to glucose.
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Purification, characterization, and kinetic analysis of a 55-kDa form of Phosphatidylinositol 4-kinase from Saccharomyces cerevisiae.
The Journal of biological chemistry, 1992Co-Authors: Joseph T. Nickels, Rosa J. Buxeda, George M. CarmanAbstract:Abstract A 55-kDa form of membrane-associated Phosphatidylinositol 4-kinase (ATP:Phosphatidylinositol 4-phosphotransferase, EC 2.7.1.67) was purified 10,166-fold from Saccharomyces cerevisiae. The purification procedure included solubilization of microsome membranes with 1% Triton X-100 followed by chromatography with DE52, hydroxylapatite I, Q-Sepharose, Mono Q, and hydroxylapatite II. The procedure resulted in a nearly homogeneous 55-kDa Phosphatidylinositol 4-kinase preparation. The 55-kDa Phosphatidylinositol 4-kinase and the previously purified 45-kDa Phosphatidylinositol 4-kinase differed with respect to their amino acid composition, isoelectric points, and peptide maps. Furthermore, the two forms of Phosphatidylinositol 4-kinase did not show an immunological relationship. Maximum 55-kDa Phosphatidylinositol 4-kinase activity was dependent on magnesium (10 mM) or manganese (0.5 mM) ions and Triton X-100 at the pH optimum of 7.0. The activation energy for the reaction was 12 kcal/mol, and the enzyme was labile above 30 degrees C. The enzyme was inhibited by thioreactive agents, MgADP, and calcium ions. A detailed kinetic analysis of the purified enzyme was performed using Triton X-100/Phosphatidylinositol-mixed micelles. 55-kDa Phosphatidylinositol 4-kinase activity followed saturation kinetics with respect to the bulk and surface concentrations of Phosphatidylinositol and followed surface dilution kinetics. The interfacial Michaelis constant (Km) and the dissociation constant (Ks) for Phosphatidylinositol in the Triton X-100 micelle surface were 1.3 mol % and 0.035 mM, respectively. The Km for MgATP was 0.36 mM. 55-kDa Phosphatidylinositol 4-kinase catalyzed a sequential reaction mechanism as indicated by the results of kinetic and isotopic exchange reactions. The enzyme bound to Phosphatidylinositol before ATP and released Phosphatidylinositol 4-phosphate before ADP. The enzymological and kinetic properties of the 55-kDa Phosphatidylinositol 4-kinase differed significantly from those of the 45-kDa Phosphatidylinositol 4-kinase. This may suggest that the two forms of Phosphatidylinositol 4-kinase from S. cerevisiae are regulated differentially in vivo.
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Phosphatidylinositol 4-kinase from yeast.
Methods in enzymology, 1992Co-Authors: George M. Carman, Charles J. Belunis, Joseph T. NickelsAbstract:Publisher Summary Phosphatidylinositol 4-kinase (1-Phosphatidylinositol kinase) catalyzes the reaction of Phosphatidylinositol with ATP to form Phosphatidylinositol 4-phosphate. Phosphatidylinositol 4-kinase (ATP:1-phosphatidyl-lD-myo-inositol 4-phosphotransferase) is the first enzyme in the phosphorylation sequence of Phosphatidylinositol leading to the formation of Phosphatidylinositol 4-phosphate and Phosphatidylinositol 4,5-bisphosphate in Saccharomyces cerevisiae (S. cerevisiae). The synthesis and turnover of the polyphosphoinositides in S. cerevisiae and in higher eukaryotes play an important role in cell growth. Phosphatidylinositol 4-kinase is associated with the microsomal, plasma membrane, and cytosolic fractions of S. cerevisiae. Phosphatidylinositol 4-kinase has been purified to near homogeneity from the microsomal fraction of S. cerevisiae by standard protein purification procedures. The chapter describes the purification and properties of the enzyme. The properties of Phosphatidylinositol 4-kinase are also discussed. Pure Phosphatidylinositol 4-kinase can be used to synthesize radiolabeled Phosphatidylinositol 4-phosphate.
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Phosphatidylinositol 4-Kinase from Saccharomyces cerevisiae
1991Co-Authors: Rosa J. Buxeda, Joseph T. Nickels, Charles J. Beluniss, George M. CarmansAbstract:Phosphatidylinositol 4-kinase (ATP:Phosphatidylinositol4-phosphotransferase, EC 2.7.1.67) was purified from Saccharomyces cerevisiae by an improved procedure over that previously reported (Belunis, C. J., Bae-Lee, M., Kelley, M. J., and Carman, G. M. (1988) J. Biol. Chem. 263, 18897-18903) for the enzyme. The molecular mass of the enzyme was 45 kDa. The 35-kDa protein previously identified as PI 4-kinase was a proteolysis product of the 45-kDa protein. A detailed kinetic analysis of the purified enzyme was performed with Triton X-lOO/Phosphatidylinositolmixed micelles according to the “surface dilution” (Deems, R. A., Eaton, B. R., and Dennis, E. A. (1975) J. Biol. Chem. 250, 9013-9020) and “dual phospholipid” (Hendrickson, H. S., and Dennis, E. A. (1984) J. Biol. Chem. 259, 5734-5739) kinetic models. Phosphatidylinositol 4-kinase activity followed saturation kinetics with respect to the bulk and surface concentrations of Phosphatidylinositol at concentrations of Phosphatidylinositol below 0.1 mM. Above 0.1 mM activity was only dependent on the surface concentration of Phosphatidylinositol. The enzyme more closely followed the dual phospholipid model where the enzyme associated with Triton X-100 micelles when Phosphatidylinositol was present. The interfacial Michaelis constant (KmB) for Phosphatidylinositol was 0.0036 mol fraction and the dissociation constant (KsA) for Phosphatidylinositol in the micelle surface was 0.26 mM. The results of glycerol gradient centrifugation studies showed that the enzyme was physically associated with Triton XlOO/Phosphatidylinositol micelles.
John E. Burke - One of the best experts on this subject based on the ideXlab platform.
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Structural Basis for Inhibitor Potency and Selectivity of Plasmodium falciparum Phosphatidylinositol 4-Kinase Inhibitors.
ACS infectious diseases, 2020Co-Authors: Stephen Fienberg, Jacob A. Mcphail, John E. Burke, Charles J. Eyermann, Lauren B. Arendse, Gregory S. Basarab, Kelly ChibaleAbstract:Plasmodium falciparum Phosphatidylinositol 4-kinase (PfPI4K) has emerged as a promising new drug target for novel antimalarial therapeutics. In the absence of a reliable high-resolution three-dimen...
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Type III Phosphatidylinositol 4 kinases: structure, function, regulation, signalling and involvement in disease
Biochemical Society transactions, 2016Co-Authors: Gillian L. Dornan, Jacob A. Mcphail, John E. BurkeAbstract:Many important cellular functions are regulated by the selective recruitment of proteins to intracellular membranes mediated by specific interactions with lipid phosphoinositides. The enzymes that generate lipid phosphoinositides therefore must be properly positioned and regulated at their correct cellular locations. Phosphatidylinositol 4 kinases (PI4Ks) are key lipid signalling enzymes, and they generate the lipid species Phosphatidylinositol 4-phosphate (PI4P), which plays important roles in regulating physiological processes including membrane trafficking, cytokinesis and organelle identity. PI4P also acts as the substrate for the generation of the signalling phosphoinositides Phosphatidylinositol 4,5-bisphosphate (PIP2) and Phosphatidylinositol 3,4,5-trisphosphate (PIP3). PI4Ks also play critical roles in a number of pathological processes including mediating replication of a number of pathogenic RNA viruses, and in the development of the parasite responsible for malaria. Key to the regulation of PI4Ks is their regulation by a variety of both host and viral protein-binding partners. We review herein our current understanding of the structure, regulatory interactions and role in disease of the type III PI4Ks. * ACBD3, : acyl-CoA-binding domain containing protein 3; NCS-1, : neuronal calcium sensor 1; NS5A, : non-structural protein 5A; PI4K, : Phosphatidylinositol 4 kinase; PI4KIIIα/β, : type III Phosphatidylinositol 4 kinase α/β; PI4P, : Phosphatidylinositol 4-phosphate; PIP2, : Phosphatidylinositol 4,5-bisphosphate; PIP3, : Phosphatidylinositol 3,4,5-trisphosphate; TGN, : trans -Golgi network; TTC7, : tetratricopeptide repeat protein 7
Radim Nencka - One of the best experts on this subject based on the ideXlab platform.
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Phosphatidylinositol 4-kinases: Function, structure, and inhibition.
Experimental cell research, 2015Co-Authors: Evzen Boura, Radim NenckaAbstract:The Phosphatidylinositol 4-kinases (PI4Ks) synthesize Phosphatidylinositol 4-phosphate (PI4P), a key member of the phosphoinositide family. PI4P defines the membranes of Golgi and trans-Golgi network (TGN) and regulates trafficking to and from the Golgi. Humans have two type II PI4Ks (α and β) and two type III enzymes (α and β). Recently, the crystal structures were solved for both type II and type III kinase revealing atomic details of their function. Importantly, the type III PI4Ks are hijacked by +RNA viruses to create so-called membranous web, an extensively phosphorylated and modified membrane system dedicated to their replication. Therefore, selective and potent inhibitors of PI4Ks have been developed as potential antiviral agents. Here we focus on the structure and function of PI4Ks and their potential in human medicine.
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The high-resolution crystal structure of Phosphatidylinositol 4-kinase IIβ and the crystal structure of Phosphatidylinositol 4-kinase IIα containing a nucleoside analogue provide a structural basis for isoform-specific inhibitor design.
Acta crystallographica. Section D Biological crystallography, 2015Co-Authors: Martin Klima, Radim Nencka, Adriana Baumlova, Dominika Chalupska, Hubert Hřebabecký, Milan Dejmek, Evzen BouraAbstract:Phosphatidylinositol 4-phosphate (PI4P) is the most abundant monophosphoinositide in eukaryotic cells. Humans have four Phosphatidylinositol 4-kinases (PI4Ks) that synthesize PI4P, among which are PI4K IIβ and PI4K IIα. In this study, two crystal structures are presented: the structure of human PI4K IIβ and the structure of PI4K IIα containing a nucleoside analogue. The former, a complex with ATP, is the first high-resolution (1.9 Å) structure of a PI4K. These structures reveal new details such as high conformational heterogeneity of the lateral hydrophobic pocket of the C-lobe and together provide a structural basis for isoform-specific inhibitor design.
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The crystal structure of the Phosphatidylinositol 4‐kinase IIα
EMBO reports, 2014Co-Authors: Adriana Baumlova, Marko Jovic, Radim Nencka, Martin Klima, Dominika Chalupska, Bartosz Róźycki, Eva Wisniewski, Anna Dubankova, Daniel P. Kloer, Tamas BallaAbstract: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 A 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.