6SL7 image
Entry Detail
PDB ID:
6SL7
Title:
The Delta Calcium mutant of ALPHA-ACTININ FROM ENTAMOEBA HISTOLYTICA
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2019-08-18
Release Date:
2020-08-26
Method Details:
Experimental Method:
Resolution:
3.30 Å
R-Value Free:
0.30
R-Value Work:
0.23
R-Value Observed:
0.23
Space Group:
P 2 2 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Calponin homology domain protein putative
Chain IDs:A
Chain Length:621
Number of Molecules:1
Biological Source:Entamoeba histolytica
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
MLZ A LYS modified residue
Ligand Molecules
Primary Citation
Calcium modulates the domain flexibility and function of an alpha-actinin similar to the ancestral alpha-actinin.
Proc.Natl.Acad.Sci.USA 117 22101 22112 (2020)
PMID: 32848067 DOI: 10.1073/pnas.1917269117

Abstact

The actin cytoskeleton, a dynamic network of actin filaments and associated F-actin-binding proteins, is fundamentally important in eukaryotes. α-Actinins are major F-actin bundlers that are inhibited by Ca2+ in nonmuscle cells. Here we report the mechanism of Ca2+-mediated regulation of Entamoeba histolytica α-actinin-2 (EhActn2) with features expected for the common ancestor of Entamoeba and higher eukaryotic α-actinins. Crystal structures of Ca2+-free and Ca2+-bound EhActn2 reveal a calmodulin-like domain (CaMD) uniquely inserted within the rod domain. Integrative studies reveal an exceptionally high affinity of the EhActn2 CaMD for Ca2+, binding of which can only be regulated in the presence of physiological concentrations of Mg2+ Ca2+ binding triggers an increase in protein multidomain rigidity, reducing conformational flexibility of F-actin-binding domains via interdomain cross-talk and consequently inhibiting F-actin bundling. In vivo studies uncover that EhActn2 plays an important role in phagocytic cup formation and might constitute a new drug target for amoebic dysentery.

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Primary Citation of related structures