8V38

Structure of the human systemic RNAi defective transmembrane protein 1 (hSIDT1)

Summary for 8V38

• Entry DOI: 10.2210/pdb8v38/pdb
• EMDB information: 42943
• Descriptor: SID1 transmembrane family member 1,RNA-directed RNA polymerase L (1 entity in total)
• Functional Keywords: rna interference, transmembrane protein, cholesterol or dsrna uptake family., membrane protein
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 2
• Total formula weight: 248196.28

Authors

Navratna, V.,Kumar, A.,Rana, J.K.,Mosalaganti, S. (deposition date: 2023-11-27, release date: 2024-06-26, Last modification date: 2024-10-23)

Primary citation

Navratna, V.,Kumar, A.,Rana, J.K.,Mosalaganti, S.
Structure of the human systemic RNAi defective transmembrane protein 1 (hSIDT1) reveals the conformational flexibility of its lipid binding domain.
Biorxiv, 2024

PubMed Abstract: In , inter-cellular transport of the small non-coding RNA causing systemic RNA interference (RNAi) is mediated by the transmembrane protein SID1, encoded by the gene in the systemic RNA interference-defective () loci. SID1 shares structural and sequence similarity with cholesterol uptake protein 1 (CHUP1) and is classified as a member of the cholesterol uptake family (ChUP). Although systemic RNAi is not an evolutionarily conserved process, the gene products are found across the animal kingdom, suggesting the existence of other novel gene regulatory mechanisms mediated by small non-coding RNAs. Human homologs of gene products - hSIDT1 and hSIDT2 - mediate contact-dependent lipophilic small non-coding dsRNA transport. Here, we report the structure of recombinant human SIDT1. We find that the extra-cytosolic domain (ECD) of hSIDT1 adopts a double jelly roll fold, and the transmembrane domain (TMD) exists as two modules - a flexible lipid binding domain (LBD) and a rigid TMD core. Our structural analyses provide insights into the inherent conformational dynamics within the lipid binding domain in cholesterol uptake (ChUP) family members.

PubMed: 38187772
DOI: 10.1101/2023.12.21.572875

Experimental method

ELECTRON MICROSCOPY (3.5 Å)