Cryo-EM structure of the diapause chaperone artemin

Amar D Parvate; Samantha M Powell; Jory T Brookreson; Trevor H Moser; Irina V Novikova; Mowei Zhou; James E Evans

doi:10.3389/fmolb.2022.998562

Cryo-EM structure of the diapause chaperone artemin

Front Mol Biosci. 2022 Nov 28:9:998562. doi: 10.3389/fmolb.2022.998562. eCollection 2022.

Authors

Amar D Parvate¹, Samantha M Powell¹, Jory T Brookreson¹, Trevor H Moser¹, Irina V Novikova¹, Mowei Zhou¹, James E Evans^{1

2}

Affiliations

¹ Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, WA, United States.
² Washington State University Pullman, School of Biological Sciences, Pullman, WA, United States.

Abstract

The protein artemin acts as both an RNA and protein chaperone and constitutes over 10% of all protein in Artemia cysts during diapause. However, its mechanistic details remain elusive since no high-resolution structure of artemin exists. Here we report the full-length structure of artemin at 2.04 Å resolution. The cryo-EM map contains density for an intramolecular disulfide bond between Cys22-Cys61 and resolves the entire C-terminus extending into the core of the assembled protein cage but in a different configuration than previously hypothesized with molecular modeling. We also provide data supporting the role of C-terminal helix F towards stabilizing the dimer form that is believed to be important for its chaperoning activity. We were able to destabilize this effect by placing a tag at the C-terminus to fully pack the internal cavity and cause limited steric hindrance.

Keywords: artemin; cell-free expression; chaperone; cryo-EM; native MS.