PDBsum entry 1mxe

Metal binding protein

PDB id: 1mxe

Contents

Protein chains

144 a.a. *

25 a.a. *

Metals

_CA ×8

Waters ×234

* Residue conservation analysis

PDB id:

1mxe

Name:

Metal binding protein

Title:

Structure of the complex of calmodulin with the target sequence of camki

Structure:

Calmodulin. Chain: a, b. Engineered: yes. Target sequence of rat calmodulin-dependent protein kinase i. Chain: e, f. Fragment: calmodulin binding domain. Synonym: cam kinase i. Engineered: yes

Source:

Drosophila melanogaster. Fruit fly. Organism_taxid: 7227. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693. Synthetic: yes. Other_details: peptide synthesis

Biol. unit:

Tetramer (from PQS)

Resolution:

1.70Å R-factor: 0.190 R-free: 0.229

Authors:

J.A.Clapperton,S.R.Martin,S.J.Smerdon,S.J.Gamblin,P.M.Bayley

Key ref:

J.A.Clapperton et al. (2002). Structure of the complex of calmodulin with the target sequence of calmodulin-dependent protein kinase I: studies of the kinase activation mechanism. Biochemistry, 41, 14669-14679. PubMed id: 12475216 DOI: 10.1021/bi026660t

Date:

02-Oct-02 Release date: 04-Dec-02

Protein chains

P62152  (CALM_DROME) -  Calmodulin from Drosophila melanogaster

Seq: 149 a.a.

Struc: 144 a.a.

Protein chains

Q63450  (KCC1A_RAT) -  Calcium/calmodulin-dependent protein kinase type 1 from Rattus norvegicus

Seq: 374 a.a.

Struc: 25 a.a.

Enzyme reactions

• Enzyme class 1: Chains A, B: E.C.?
• Enzyme class 2: Chains E, F: E.C.2.7.11.17 - calcium/calmodulin-dependent protein kinase.
• Reaction:
  1. L-seryl-[protein] + ATP = O-phospho-L-seryl-[protein] + ADP + H⁺
  2. L-threonyl-[protein] + ATP = O-phospho-L-threonyl-[protein] + ADP + H⁺
• Cofactor: Ca(2+)

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1021/bi026660t

Biochemistry 41:14669-14679 (2002)

PubMed id: 12475216

Structure of the complex of calmodulin with the target sequence of calmodulin-dependent protein kinase I: studies of the kinase activation mechanism.

J.A.Clapperton, S.R.Martin, S.J.Smerdon, S.J.Gamblin, P.M.Bayley.

ABSTRACT

Calcium-saturated calmodulin (CaM) directly activates CaM-dependent protein kinase I (CaMKI) by binding to a region in the C-terminal regulatory sequence of the enzyme to relieve autoinhibition. The structure of CaM in a high-affinity complex with a 25-residue peptide of CaMKI (residues 294-318) has been determined by X-ray crystallography at 1.7 A resolution. Upon complex formation, the CaMKI peptide adopts an alpha-helical conformation, while changes in the CaM domain linker enable both its N- and C-domains to wrap around the peptide helix. Target peptide residues Trp-303 (interacting with the CaM C-domain) and Met-316 (with the CaM N-domain) define the mode of binding as 1-14. In addition, two basic patches on the peptide form complementary charge interactions with CaM. The CaM-peptide affinity is approximately 1 pM, compared with 30 nM for the CaM-kinase complex, indicating that activation of autoinhibited CaMKI by CaM requires a costly energetic disruption of the interactions between the CaM-binding sequence and the rest of the enzyme. We present biochemical and structural evidence indicating the involvement of both CaM domains in the activation process: while the C-domain exhibits tight binding toward the regulatory sequence, the N-domain is necessary for activation. Our crystal structure also enables us to identify the full CaM-binding sequence. Residues Lys-296 and Phe-298 from the target peptide interact directly with CaM, demonstrating overlap between the autoinhibitory and CaM-binding sequences. Thus, the kinase activation mechanism involves the binding of CaM to residues associated with the inhibitory pseudosubstrate sequence.