2JU0

Structure of Yeast Frequenin bound to PdtIns 4-kinase

Summary for 2JU0

• Entry DOI: 10.2210/pdb2ju0/pdb
• Descriptor: Calcium-binding protein NCS-1, Phosphatidylinositol 4-kinase PIK1, CALCIUM ION (3 entities in total)
• Functional Keywords: ef-hand, calcium, ptdins 4-kinase, frequenin, yeast, lipoprotein, membrane, myristate, nucleus, phosphorylation, transferase, metal binding protein-signaling protein complex, metal binding protein/signaling protein
• Biological source: Saccharomyces cerevisiae (baker's yeast); More
• Cellular location: Bud membrane; Peripheral membrane protein: Q06389; Nucleus: P39104
• Total number of polymer chains: 2
• Total formula weight: 27788.62

Authors

Ames, J. (deposition date: 2007-08-11, release date: 2007-08-28, Last modification date: 2024-05-29)

Primary citation

Strahl, T.,Huttner, I.G.,Lusin, J.D.,Osawa, M.,King, D.,Thorner, J.,Ames, J.B.
Structural insights into activation of phosphatidylinositol 4-kinase (Pik1) by yeast frequenin (Frq1).
J.Biol.Chem., 282:30949-30959, 2007

PubMed Abstract: Yeast frequenin (Frq1), a small N-myristoylated EF-hand protein, activates phosphatidylinositol 4-kinase Pik1. The NMR structure of Ca2+-bound Frq1 complexed to an N-terminal Pik1 fragment (residues 121-174) was determined. The Frq1 main chain is similar to that in free Frq1 and related proteins in the same branch of the calmodulin superfamily. The myristoyl group and first eight residues of Frq1 are solvent-exposed, and Ca2+ binds the second, third, and fourth EF-hands, which associate to create a groove with two pockets. The Pik1 peptide forms two helices (125-135 and 156-169) connected by a 20-residue loop. Side chains in the Pik1 N-terminal helix (Val-127, Ala-128, Val-131, Leu-132, and Leu-135) interact with solvent-exposed residues in the Frq1 C-terminal pocket (Leu-101, Trp-103, Val-125, Leu-138, Ile-152, and Leu-155); side chains in the Pik1 C-terminal helix (Ala-157, Ala-159, Leu-160, Val-161, Met-165, and Met-167) contact solvent-exposed residues in the Frq1 N-terminal pocket (Trp-30, Phe-34, Phe-48, Ile-51, Tyr-52, Phe-55, Phe-85, and Leu-89). This defined complex confirms that residues in Pik1 pinpointed as necessary for Frq1 binding by site-directed mutagenesis are indeed sufficient for binding. Removal of the Pik1 N-terminal region (residues 8-760) from its catalytic domain (residues 792-1066) abolishes lipid kinase activity, inconsistent with Frq1 binding simply relieving an autoinhibitory constraint. Deletion of the lipid kinase unique motif (residues 35-110) also eliminates Pik1 activity. In the complex, binding of Ca2+-bound Frq1 forces the Pik1 chain into a U-turn. Frq1 may activate Pik1 by facilitating membrane targeting via the exposed N-myristoyl group and by imposing a structural transition that promotes association of the lipid kinase unique motif with the kinase domain.

PubMed: 17720810
DOI: 10.1074/jbc.M705499200

Experimental method

SOLUTION NMR