2vhq

P4 PROTEIN FROM BACTERIOPHAGE PHI12 S252A mutant in complex with ATP AND MG

spinqualitylabelsall models 2vhq, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2vhq is a 3 chain structure with sequence from Pseudomonas phage phi12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.15Å Ligands: ATP, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q94M05_9VIRU Publication Abstract from PubMed The P4 protein of bacteriophage varphi12 is a hexameric molecular motor closely related to superfamily 4 helicases. P4 converts chemical energy from ATP hydrolysis into mechanical work, to translocate single-stranded RNA into a viral capsid. The molecular basis of mechanochemical coupling, i.e. how small approximately 1 A changes in the ATP-binding site are amplified into nanometer scale motion along the nucleic acid, is not understood at the atomic level. Here we study in atomic detail the mechanochemical coupling using structural and biochemical analyses of P4 mutants. We show that a conserved region, consisting of superfamily 4 helicase motifs H3 and H4 and loop L2, constitutes the moving lever of the motor. The lever tip encompasses an RNA-binding site that moves along the mechanical reaction coordinate. The lever is flanked by gamma-phosphate sensors (Asn-234 and Ser-252) that report the nucleotide state of neighboring subunits and control the lever position. Insertion of an arginine finger (Arg-279) into the neighboring catalytic site is concomitant with lever movement and commences ATP hydrolysis. This ensures cooperative sequential hydrolysis that is tightly coupled to mechanical motion. Given the structural conservation, the mutated residues may play similar roles in other hexameric helicases and related molecular motors. Structural Basis of Mechanochemical Coupling in a Hexameric Molecular Motor.,Kainov DE, Mancini EJ, Telenius J, Lisal J, Grimes JM, Bamford DH, Stuart DI, Tuma R J Biol Chem. 2008 Feb 8;283(6):3607-3617. Epub 2007 Dec 5. PMID:18057007 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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