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8qmp

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

Structural highlights

8qmp is a 1 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Electron Microscopy, Resolution 3.3Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

ACA8_ARATH This magnesium-dependent enzyme catalyzes the hydrolysis of ATP coupled with the translocation of calcium from the cytosol out of the cell.

Publication Abstract from PubMed

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 (Delta20, Delta30, Delta35, Delta37, Delta40, Delta74 and Delta100) to explore the role of conserved motifs in the N-terminal segment preceding the calmodulin binding sites. Furthermore, we purified WT, Delta20- and Delta100-ACA8, tested activity in vitro and performed structural studies of purified Delta20-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 A 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.

Conserved N-terminal Regulation of the ACA8 Calcium Pump with Two Calmodulin Binding Sites.,Larsen ST, Dannerso JK, Nielsen CJF, Poulsen LR, Palmgren M, Nissen P J Mol Biol. 2024 Oct 15;436(20):168747. doi: 10.1016/j.jmb.2024.168747. Epub 2024 , Aug 20. PMID:39168442^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Larsen ST, Dannersø JK, Nielsen CJF, Poulsen LR, Palmgren M, Nissen P. Conserved N-terminal Regulation of the ACA8 Calcium Pump with Two Calmodulin Binding Sites. J Mol Biol. 2024 Oct 15;436(20):168747. PMID:39168442 doi:10.1016/j.jmb.2024.168747