8QMP

Structure of the E2 Beryllium Fluoride Complex of the Autoinhibited Calcium ATPase ACA8

Summary for 8QMP

• Entry DOI: 10.2210/pdb8qmp/pdb
• EMDB information: 18506
• Descriptor: Calcium-transporting ATPase 8, plasma membrane-type, MAGNESIUM ION, BERYLLIUM TRIFLUORIDE ION (3 entities in total)
• Functional Keywords: hydrolase calcium transporter p-type atpase, hydrolase, transport protein
• Biological source: Arabidopsis thaliana (thale cress)
• Total number of polymer chains: 1
• Total formula weight: 114323.83

Authors

Thirup Larsen, S.,Karlsen Dannersoe, J.,Nissen, P. (deposition date: 2023-09-25, release date: 2024-10-02, Last modification date: 2024-10-23)

Primary citation

Larsen, S.T.,Dannerso, J.K.,Nielsen, C.J.F.,Poulsen, L.R.,Palmgren, M.,Nissen, P.
Conserved N-terminal Regulation of the ACA8 Calcium Pump with Two Calmodulin Binding Sites.
J.Mol.Biol., 436:168747-168747, 2024

PubMed Abstract: The autoinhibited plasma membrane calcium ATPase ACA8 from A. thaliana has an N-terminal autoinhibitory domain. Binding of calcium-loaded calmodulin at two sites located at residues 42-62 and 74-96 relieves autoinhibition of ACA8 activity. Through activity studies and a yeast complementation assay we investigated wild-type (WT) and N-terminally truncated ACA8 constructs (Δ20, Δ30, Δ35, Δ37, Δ40, Δ74 and Δ100) to explore the role of conserved motifs in the N-terminal segment preceding the calmodulin binding sites. Furthermore, we purified WT, Δ20- and Δ100-ACA8, tested activity in vitro and performed structural studies of purified Δ20-ACA8 stabilized in a lipid nanodisc to explore the mechanism of autoinhibition. We show that an N-terminal segment between residues 20 and 35 including conserved Phe32, upstream of the calmodulin binding sites, is important for autoinhibition and the activation by calmodulin. Cryo-EM structure determination at 3.3 Å resolution of a beryllium fluoride inhibited E2 form, and at low resolution for an E1 state combined with AlphaFold prediction provide a model for autoinhibition, consistent with the mutational studies.

PubMed: 39168442
DOI: 10.1016/j.jmb.2024.168747

Experimental method

ELECTRON MICROSCOPY (3.3 Å)