Structural highlights
FunctionPublication Abstract from PubMedChannel enzymes represent a class of ion channels with enzymatic activity directly or indirectly linked to their channel function. We investigated a TRPM2 chanzyme from choanoflagellates that integrates two seemingly incompatible functions into a single peptide: a channel module activated by ADP-ribose with high open probability and an enzyme module (NUDT9-H domain) consuming ADP-ribose at a remarkably slow rate. Using time-resolved cryogenic-electron microscopy, we captured a complete series of structural snapshots of gating and catalytic cycles, revealing the coupling mechanism between channel gating and enzymatic activity. The slow kinetics of the NUDT9-H enzyme module confers a self-regulatory mechanism: ADPR binding triggers NUDT9-H tetramerization, promoting channel opening, while subsequent hydrolysis reduces local ADPR, inducing channel closure. We further demonstrated how the NUDT9-H domain has evolved from a structurally semi-independent ADP-ribose hydrolase module in early species to a fully integrated component of a gating ring essential for channel activation in advanced species. Coupling enzymatic activity and gating in an ancient TRPM chanzyme and its molecular evolution.,Huang Y, Kumar S, Lee J, Lu W, Du J Nat Struct Mol Biol. 2024 May 21. doi: 10.1038/s41594-024-01316-4. PMID:38773335[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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