PDBsum entry 4yga

Metal binding protein

PDB id: 4yga

Contents

Protein chains

448 a.a.

124 a.a.

Metals

_CA ×16

PDB id:

4yga

Name:

Metal binding protein

Title:

Cdpk1, from toxoplasma gondii, bound to inhibitory vhh-1b7

Structure:

Calmodulin-domain protein kinase 1. Chain: a, c, e, g. Engineered: yes. Vhh-1b7. Chain: b, d, f, h. Engineered: yes

Source:

Toxoplasma gondii. Organism_taxid: 5811. Gene: cdpk1. Expressed in: escherichia coli. Expression_system_taxid: 469008. Vicugna pacos. Organism_taxid: 30538.

Resolution:

2.94Å R-factor: 0.227 R-free: 0.262

Authors:

K.E.Knockenhauer,T.U.Schwartz

Key ref:

J.R.Ingram et al. (2015). Allosteric activation of apicomplexan calcium-dependent protein kinases. Proc Natl Acad Sci U S A, 112, E4975. PubMed id: 26305940 DOI: 10.1073/pnas.1505914112

Date:

26-Feb-15 Release date: 26-Aug-15

Protein chains

Q9BJF5  (Q9BJF5_TOXGO) -  Calmodulin-domain protein kinase 1 from Toxoplasma gondii

Seq: 507 a.a.

Struc: 448 a.a.

Protein chains

No UniProt id for this chain

Struc: 124 a.a.

DOI no: 10.1073/pnas.1505914112

Proc Natl Acad Sci U S A 112:E4975 (2015)

PubMed id: 26305940

Allosteric activation of apicomplexan calcium-dependent protein kinases.

J.R.Ingram, K.E.Knockenhauer, B.M.Markus, J.Mandelbaum, A.Ramek, Y.Shan, D.E.Shaw, T.U.Schwartz, H.L.Ploegh, S.Lourido.

ABSTRACT

Calcium-dependent protein kinases (CDPKs) comprise the major group of Ca(2+)-regulated kinases in plants and protists. It has long been assumed that CDPKs are activated, like other Ca(2+)-regulated kinases, by derepression of the kinase domain (KD). However, we found that removal of the autoinhibitory domain from Toxoplasma gondii CDPK1 is not sufficient for kinase activation. From a library of heavy chain-only antibody fragments (VHHs), we isolated an antibody (1B7) that binds TgCDPK1 in a conformation-dependent manner and potently inhibits it. We uncovered the molecular basis for this inhibition by solving the crystal structure of the complex and simulating, through molecular dynamics, the effects of 1B7-kinase interactions. In contrast to other Ca(2+)-regulated kinases, the regulatory domain of TgCDPK1 plays a dual role, inhibiting or activating the kinase in response to changes in Ca(2+) concentrations. We propose that the regulatory domain of TgCDPK1 acts as a molecular splint to stabilize the otherwise inactive KD. This dependence on allosteric stabilization reveals a novel susceptibility in this important class of parasite enzymes.