1jlu
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(New page: 200px<br /><applet load="1jlu" size="450" color="white" frame="true" align="right" spinBox="true" caption="1jlu, resolution 2.25Å" /> '''Crystal Structure of...)
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Revision as of 16:15, 20 November 2007
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Crystal Structure of the Catalytic Subunit of cAMP-dependent Protein Kinase Complexed with a Phosphorylated Substrate Peptide and Detergent
Overview
The crystal structure of ternary and binary substrate complexes of the, catalytic subunit of cAMP-dependent protein kinase has been refined at 2.2, and 2.25 A resolution, respectively. The ternary complex contains ADP and, a 20-residue substrate peptide, whereas the binary complex contains the, phosphorylated substrate peptide. These 2 structures were refined to, crystallographic R-factors of 17.5 and 18.1%, respectively. In the ternary, complex, the hydroxyl oxygen OG of the serine at the P-site is 2.7 A from, the OD1 atom of Asp 166. This is the first crystallographic evidence, showing the direct interaction of this invariant carboxylate with a, peptide substrate, and supports the predicted role of Asp 166 as a, catalytic base and as an agent to position the serine -OH for nucleophilic, attack. A comparison of the substrate and inhibitor ternary complexes, places the hydroxyl oxygen of the serine 2.7 A from the gamma-phosphate of, ATP and supports a direct in-line mechanism for phosphotransfer. In the, binary complex, the phosphate on the Ser interacts directly with the, epsilon N of Lys 168, another conserved residue. In the ternary complex, containing ATP and the inhibitor peptide, Lys 168 interacts, electrostatically with the gamma-phosphate of ATP (Zheng J, Knighton DR, Ten Eyck LF, Karlsson R, Xuong NH, Taylor SS, Sowadski JM, 1993, Biochemistry 32:2154-2161). Thus, Lys 168 remains closely associated with, the phosphate in both complexes. A comparison of this binary complex, structure with the recently solved structure of the ternary complex, containing ATP and inhibitor peptide also reveals that the phosphate atom, traverses a distance of about 1.5 A following nucleophilic attack by, serine and transfer to the peptide. No major conformational changes of, active site residues are seen when the substrate and product complexes are, compared, although the binary complex with the phosphopeptide reveals, localized changes in conformation in the region corresponding to the, glycine-rich loop. The high B-factors for this loop support the conclusion, that this structural motif is a highly mobile segment of the protein.
About this Structure
1JLU is a Protein complex structure of sequences from Mus musculus with OCT as ligand. Active as Non-specific serine/threonine protein kinase, with EC number 2.7.11.1 Full crystallographic information is available from OCA.
Reference
cAMP-dependent protein kinase: crystallographic insights into substrate recognition and phosphotransfer., Madhusudan, Trafny EA, Xuong NH, Adams JA, Ten Eyck LF, Taylor SS, Sowadski JM, Protein Sci. 1994 Feb;3(2):176-87. PMID:8003955
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