4YGA

CDPK1, from Toxoplasma gondii, bound to inhibitory VHH-1B7

Summary for 4YGA

• Entry DOI: 10.2210/pdb4yga/pdb
• Descriptor: Calmodulin-domain protein kinase 1, VHH-1B7, CALCIUM ION (3 entities in total)
• Functional Keywords: serine/threonine protein kinase, vhh domain, inhibitor, metal binding protein
• Biological source: Toxoplasma gondii; More
• Total number of polymer chains: 8
• Total formula weight: 296551.59

Authors

Knockenhauer, K.E.,Schwartz, T.U. (deposition date: 2015-02-26, release date: 2015-08-26, Last modification date: 2024-11-06)

Primary citation

Ingram, J.R.,Knockenhauer, K.E.,Markus, B.M.,Mandelbaum, J.,Ramek, A.,Shan, Y.,Shaw, D.E.,Schwartz, T.U.,Ploegh, H.L.,Lourido, S.
Allosteric activation of apicomplexan calcium-dependent protein kinases.
Proc.Natl.Acad.Sci.USA, 112:E4975-E4984, 2015

PubMed Abstract: Calcium-dependent protein kinases (CDPKs) comprise the major group of Ca2+-regulated kinases in plants and protists. It has long been assumed that CDPKs are activated, like other Ca2+-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 Ca2+-regulated kinases, the regulatory domain of TgCDPK1 plays a dual role, inhibiting or activating the kinase in response to changes in Ca2+ 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.

PubMed: 26305940
DOI: 10.1073/pnas.1505914112

Experimental method

X-RAY DIFFRACTION (2.94 Å)