1syk

From Proteopedia

Revision as of 00:43, 21 November 2007

Crystal structure of E230Q mutant of cAMP-dependent protein kinase reveals unexpected apoenzyme conformation

Overview

Glu230, one of the acidic residues that cluster around the active site of, the catalytic subunit of cAMP-dependent protein kinase, plays an important, role in substrate recognition. Specifically, its side chain forms a direct, salt-bridge interaction with the substrate's P-2 Arg. Previous studies, showed that mutation of Glu230 to Gln (E230Q) caused significant decreases, not only in substrate binding but also in the rate of phosphoryl transfer., To better understand the importance of Glu230 for structure and function, we solved the crystal structure of the E230Q mutant at 2.8 A resolution., Surprisingly, the mutant preferred an open conformation with no bound, ligands observed, even though the crystals were grown in the presence of, MgATP and the inhibitor peptide, IP20. This is in contrast to the, wild-type protein that, under the same conditions, prefers the closed, conformation of a ternary complex. The structure highlights the importance, of the electrostatic surface not only for substrate binding and catalysis, but also for the mechanism for closing the active site cleft. This surface, mutation clearly disrupts the recognition and binding of substrate peptide, so that the enzyme prefers an open conformation that cannot trap ATP. This, is consistent with the reinforcing concepts of conformational dynamics and, the synergistic binding of ATP and substrate peptide. Another unusual, feature of the structure is the observation of the entire N terminus, (Gly1-Thr32) assumes an extended alpha-helix conformation. Finally, based, on temperature factors, this mutant structure is more stable than the, wild-type C-subunit in the apo state.

About this Structure

1SYK is a Single protein structure of sequence from Mus musculus. Active as Non-specific serine/threonine protein kinase, with EC number 2.7.11.1 Full crystallographic information is available from OCA.

Reference

Crystal structure of the E230Q mutant of cAMP-dependent protein kinase reveals an unexpected apoenzyme conformation and an extended N-terminal A helix., Wu J, Yang J, Kannan N, Madhusudan, Xuong NH, Ten Eyck LF, Taylor SS, Protein Sci. 2005 Nov;14(11):2871-9. PMID:16253959

Page seeded by OCA on Wed Nov 21 02:51:05 2007