8HAD image
Deposition Date 2022-10-26
Release Date 2024-05-15
Last Version Date 2024-06-26
Entry Detail
PDB ID:
8HAD
Keywords:
Title:
A novel dimer configuration of a diatom Get3 forming a tetrameric complex with its tail-anchored membrane cargo
Biological Source:
Source Organism:
Host Organism:
Method Details:
Experimental Method:
Resolution:
3.81 Å
R-Value Free:
0.36
R-Value Work:
0.32
R-Value Observed:
0.32
Space Group:
I 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:ATPase ASNA1 homolog
Gene (Uniprot):PHATRDRAFT_22896
Chain IDs:A, B
Chain Length:349
Number of Molecules:2
Biological Source:Phaeodactylum tricornutum CCAP 1055/1
Ligand Molecules
Primary Citation
A distinct dimer configuration of a diatom Get3 forming a tetrameric complex with its tail-anchored membrane cargo.
Bmc Biol. 22 136 136 (2024)
PMID: 38867239 DOI: 10.1186/s12915-024-01933-x

Abstact

BACKGROUND Most tail-anchored (TA) membrane proteins are delivered to the endoplasmic reticulum through a conserved posttranslational pathway. Although core mechanisms underlying the targeting and insertion of TA proteins are well established in eukaryotes, their role in mediating TA protein biogenesis in plants remains unclear. We reported the crystal structures of algal arsenite transporter 1 (ArsA1), which possesses an approximately 80-kDa monomeric architecture and carries chloroplast-localized TA proteins. However, the mechanistic basis of ArsA2, a Get3 (guided entry of TA proteins 3) homolog in plants, for TA recognition remains unknown. RESULTS Here, for the first time, we present the crystal structures of the diatom Pt-Get3a that forms a distinct ellipsoid-shaped tetramer in the open (nucleotide-bound) state through crystal packing. Pulldown assay results revealed that only tetrameric Pt-Get3a can bind to TA proteins. The lack of the conserved zinc-coordination CXXC motif in Pt-Get3a potentially leads to the spontaneous formation of a distinct parallelogram-shaped dimeric conformation in solution, suggesting a new dimer state for subsequent tetramerization upon TA targeting. Pt-Get3a nonspecifically binds to different subsets of TA substrates due to the lower hydrophobicity of its α-helical subdomain, which is implicated in TA recognition. CONCLUSIONS Our study provides new insights into the mechanisms underlying TA protein shielding by tetrameric Get3 during targeting to the diatom's cell membrane.

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Primary Citation of related structures