Platform-directed allostery and quaternary structure dynamics of SAMHD1 catalysis

Acton, Oliver J.; Sheppard, Devon; Kunzelmann, Simone; Caswell, Sarah J.; Nans, Andrea; Burgess, Ailidh J. O.; Kelly, Geoff; Morris, Elizabeth R.; Rosenthal, Peter B.; Taylor, Ian A.

Abstract

SAMHD1 regulates cellular nucleotide homeostasis, controlling dNTP levels by catalysing their hydrolysis into 2’-deoxynucleosides and triphosphate. In differentiated CD4+ macrophage and resting T-cells SAMHD1 activity results in the inhibition of HIV-1 infection through a dNTP blockade. In cancer, SAMHD1 desensitizes cells to nucleoside-analogue chemotherapies. Here we employ time-resolved cryogenic-EM imaging and single-particle analysis to visualise assembly, allostery and catalysis by this multi-subunit enzyme. Our observations reveal how dynamic conformational changes in the SAMHD1 quaternary structure drive the catalytic cycle. We capture five states at high-resolution in a live catalytic reaction, revealing how allosteric activators support assembly of a stable SAMHD1 tetrameric core and how catalysis is driven by the opening and closing of active sites through pairwise coupling of active sites and order-disorder transitions in regulatory domains. This direct visualisation of enzyme catalysis dynamics within an allostery-stabilised platform sets a precedent for mechanistic studies into the regulation of multi-subunit enzymes.

Citation

Acton, O. J., Sheppard, D., Kunzelmann, S., Caswell, S. J., Nans, A., Burgess, A. J. O., …Taylor, I. A. (2024). Platform-directed allostery and quaternary structure dynamics of SAMHD1 catalysis. Nature Communications, 15(1), Article 3775. https://doi.org/10.1038/s41467-024-48237-w

• Journal Article Type: Article
• Acceptance Date: Apr 25, 2024
• Online Publication Date: May 6, 2024
• Publication Date: May 6, 2024
• Deposit Date: May 7, 2024
• Publicly Available Date: May 8, 2024
• Journal: Nature Communications
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 15
• Issue: 1
• Article Number: 3775
• DOI: https://doi.org/10.1038/s41467-024-48237-w
• Public URL: https://durham-repository.worktribe.com/output/2433897