Synthesis and Effect of Conformationally Locked Carbocyclic Guanine Nucleotides on Dynamin. Author Kiran Toti, John Jimah, Veronica Salmaso, Jenny Hinshaw, Kenneth Jacobson Publication Year 2022 Type Journal Article Abstract Guanine nucleotides can flip between a North and South conformation in the ribose moiety. To test the enzymatic activity of GTPases bound to nucleotides in the two conformations, we generated methanocarba guanine nucleotides in the North or South envelope conformations, i.e., (N)-GTP and (S)-GTP, respectively. With dynamin as a model system, we examined the effects of (N)-GTP and (S)-GTP on dynamin-mediated membrane constriction, an activity essential for endocytosis. Dynamin membrane constriction and fission activity are dependent on GTP binding and hydrolysis, but the effect of the conformational state of the GTP nucleotide on dynamin activity is not known. After reconstituting dynamin-mediated lipid tubulation and membrane constriction in vitro, we observed via cryo-electron microscopy (cryo-EM) that (N)-GTP, but not (S)-GTP, enables the constriction of dynamin-decorated lipid tubules. These findings suggest that the activity of dynamin is dependent on the conformational state of the GTP nucleotide. However, a survey of nucleotide ribose conformations associated with dynamin structures in nature shows almost exclusively the (S)-conformation. The explanation for this mismatch of (N) vs. (S) required for GTP analogues in a dynamin-mediated process will be addressed in future studies. Keywords Cryoelectron Microscopy, Guanosine Triphosphate, Lipids, Dynamins, Guanine Nucleotides, Ribose Journal Biomolecules Volume 12 Issue 4 Date Published 2022 Apr 16 ISSN Number 2218-273X DOI 10.3390/biom12040584 Alternate Journal Biomolecules PMCID PMC9031165 PMID 35454173 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML