Crystal Structures of RI Subunit of Cyclic Adenosine 5'-Monophosphate (cAMP)-Dependent Protein Kinase Complexed with (Rp
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- 作者：Jian Wu ; John M. Jones ; Nguyen-Huu Xuong ; Lynn F. Ten Eyck ; and Susan S. Taylor
- 刊名：Biochemistry
- 出版年：2004
- 出版时间：June 1, 2004
- 年：2004
- 卷：43
- 期：21
- 页码：6620 - 6629
- 全文大小：468K
- 年卷期：v.43,no.21(June 1, 2004)
- ISSN：1520-4995
文摘
Cyclic adenosine 5'-monophosphate (cAMP) is an ancient signaling molecule, and in vertebrates,a primary target for cAMP is cAMP-dependent protein kinase (PKA). (Rp)-adenosine 3',5'-cyclicmonophosphothioate ((Rp)-cAMPS) and its analogues are the only known competitive inhibitors andantagonists for cAMP activation of PKA, while (Sp)-adenosine 3',5'-cyclic monophosphothioate ((Sp)-cAMPS) functions as an agonist. The crystal structures of a 
(1-91) deletion mutant of the RI
regulatorysubunit of PKA bound to (Rp)-cAMPS and (Sp)-cAMPS were determined at 2.4 and 2.3 Å resolution,respectively. While the structures are similar to each other and to the crystal structure of RI bound tocAMP, differences in the dynamical properties of the protein when (Rp)-cAMPS is bound are apparent.The structures highlight the critical importance of the exocyclic oxygen's interaction with the invariantarginine in the phosphate binding cassette (PBC) and the importance of this interaction for the dynamicalproperties of the interactions that radiate out from the PBC. The conformations of the phosphate bindingcassettes containing two invariant arginine residues (Arg209 on domain A, and Arg333 on domain B) aresomewhat different due to the sulfur interacting with this arginine. Furthermore, the B-site ligand togetherwith the entire domain B show significant differences in their overall dynamic properties in the crystalstructure of (1-91) RI complexed with (Rp)-cAMPS phosphothioate analogue ((Rp)-RI) comparedto the cAMP- and (Sp)-cAMPS-bound type I and II regulatory subunits, based on the temperature factors.In all structures, two structural solvent molecules exist within the A-site ligand binding pocket; bothmediate water-bridged interactions between the ligand and the protein. No structured waters are in theB-site pocket. Owing to the higher resolution data, the N-terminal segment (109-117) of the RI subunitcan also be traced. This strand forms an intermolecular antiparallel 
beta2.gif" BORDER=0 ALIGN="middle">-sheet with the same strand in anadjacent molecule and implies that the RI subunit can form a weak homodimer even in the absence ofits dimerization domain.
(1-91) deletion mutant of the RI regulatorysubunit of PKA bound to (Rp)-cAMPS and (Sp)-cAMPS were determined at 2.4 and 2.3 Å resolution,respectively. While the structures are similar to each other and to the crystal structure of RI bound tocAMP, differences in the dynamical properties of the protein when (Rp)-cAMPS is bound are apparent.The structures highlight the critical importance of the exocyclic oxygen's interaction with the invariantarginine in the phosphate binding cassette (PBC) and the importance of this interaction for the dynamicalproperties of the interactions that radiate out from the PBC. The conformations of the phosphate bindingcassettes containing two invariant arginine residues (Arg209 on domain A, and Arg333 on domain B) aresomewhat different due to the sulfur interacting with this arginine. Furthermore, the B-site ligand togetherwith the entire domain B show significant differences in their overall dynamic properties in the crystalstructure of (1-91) RI complexed with (Rp)-cAMPS phosphothioate analogue ((Rp)-RI) comparedto the cAMP- and (Sp)-cAMPS-bound type I and II regulatory subunits, based on the temperature factors.In all structures, two structural solvent molecules exist within the A-site ligand binding pocket; bothmediate water-bridged interactions between the ligand and the protein. No structured waters are in theB-site pocket. Owing to the higher resolution data, the N-terminal segment (109-117) of the RI subunitcan also be traced. This strand forms an intermolecular antiparallel beta2.gif" BORDER=0 ALIGN="middle">-sheet with the same strand in anadjacent molecule and implies that the RI subunit can form a weak homodimer even in the absence ofits dimerization domain.