skip to main content

SciTech ConnectSciTech Connect

Title: Allosteric activation of apicomplexan calcium-dependent protein kinases

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.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [3] ;  [4] ;  [2] ;  [5] ; ORCiD logo [1]
  1. Whitehead Inst. for Biomedical Research, Cambridge, MA (United States)
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Biology
  3. D. E. Shaw Research, New York, NY (United States)
  4. D. E. Shaw Research, New York, NY (United States); Columbia Univ., New York, NY (United States). Dept. of Biochemistry and Molecular Biophysics
  5. Whitehead Inst. for Biomedical Research, Cambridge, MA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Biology
Publication Date:
OSTI Identifier:
1214843
Grant/Contract Number:
AC02-06CH11357; GM103403; T32GM007287; 1122374; 1DP5OD017892
Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 36; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Whitehead Inst. for Biomedical Research, Cambridge, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Inst. of Health (NIH) (United States); National Science Foundation (NSF); German Academic Exchange Service (Germany)
Contributing Orgs:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); D. E. Shaw Research, New York, NY (United States); Columbia Univ., New York, NY (United States)
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES; calcium-dependent protein kinase; kinase activation; VHH