A molten globule ensemble primes Arf1-GDP for the nucleotide switch

• 成果类型: Article
• 署名作者: Koduru, Tejaswi; Hantman, Noam; Peters, Edgar V.; Jaworek, Michel W.; Wang, Jinqiu; Zhang, Siwen; McCallum, Scott A.; Gillilan, Richard E.; Fossat, Martin J.; Roumestand, Christian; Sagar, Amin; Winter, Roland; Bernado, Pau; Cherfils, Jacqueline; Royer, Catherine A.
• 署名单位: Rensselaer Polytechnic Institute; Rensselaer Polytechnic Institute; Rensselaer Polytechnic Institute; Dortmund University of Technology; Rensselaer Polytechnic Institute; Cornell University; Max Planck Society; Universite de Montpellier; Institut National de la Sante et de la Recherche Medicale (Inserm); Centre National de la Recherche Scientifique (CNRS); Universite Paris Saclay; Centre National de la Recherche Scientifique (CNRS)
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11826
• DOI: 10.1073/pnas.2413100121
• 发表日期: 2024-09-24
• 关键词: gtp-binding proteins; chemical-exchange; structural basis; arf family; conformational switch; crystal-structure; nmr-spectroscopy; pressure; activation; relaxation

摘要

The adenosine di- phosphate (ADP) ribosylation factor (Arf) small guanosine tri- phosphate (GTP)ases function as molecular switches to activate signaling cascades that control membrane organization in eukaryotic cells. In Arf1, the GDP/GTP switch does not occur spontaneously but requires guanine nucleotide exchange factors (GEFs) and membranes. Exchange involves massive conformational changes, including disruption of the core (3- sheet. The mechanisms by which this energetically costly switch occurs remain to be elucidated. To probe the switch mechanism, we coupled pressure perturbation with nuclear magnetic resonance (NMR), Fourier Transform infra- red spectroscopy (FTIR), small- angle X- ray scattering (SAXS), fluorescence, and computation. Pressure induced the formation of a classical molten globule (MG) ensemble. Pressure also favored the GDP to GTP transition, providing strong support for the notion that the MG ensemble plays a functional role in the nucleotide switch. We propose that the MG ensemble allows for switching without the requirement for complete unfolding and may be recognized by GEFs. An MG- based switching mechanism could constitute a pervasive feature in Arfs and Arf-like GTPases, and more generally, the evolutionarily related (Ras- like small GTPases) Rags and G alpha GTPases.