Cyclic peptide inhibitors function as molecular glues to stabilize Gq/ 11 heterotrimers

• 成果类型: Article
• 署名作者: Muhle, Jonas; Alenfelder, Judith; Rodrigues, Matthew J.; Juergenliemke, Lars; Guixa-Gonzalez, Ramon; Graetz, Lukas; Andres, Fabio; Bacchin, Arianna; Hennig, Michael; Schihada, Hannes; Cruesemann, Max; Koenig, Gabriele M.; Schertler, Gebhard; Kostenis, Evi; Deupi, Xavier
• 署名单位: University of Bonn; University of Bonn; Swiss Institute of Bioinformatics; Consejo Superior de Investigaciones Cientificas (CSIC); CSIC - Centro de Investigacion y Desarrollo Pascual Vila (CID-CSIC); CSIC - Instituto de Quimica Avanzada de Cataluna (IQAC); Philipps University Marburg; University of Bonn; Goethe University Frankfurt
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9201
• 发表日期: 2025-05-13
• 关键词: g-proteins; alpha-subunit; toxin; activation; mutations; mechanism; identification; transducin; gtp

摘要

Heterotrimeric G alpha:Gfa gamma G proteins function as molecular switches downstream of G protein-coupled receptors (GPCRs). They alternate between a heterotrimeric GDP- bound OFF- state and a GTP- bound ON- state in which G alpha GTP is separated from the Gfa gamma dimer. Consequently, pharmacological tools to securely prevent the OFF- ON transition are of utmost importance to investigate their molecular switch function, specific contribution to GPCR signal transduction, and potential as drug targets. FR900359 (FR) and YM- 254890 (YM), two natural cyclic peptides and highly specific inhibitors of Gq/11 heterotrimers, are exactly such tools. To date, their efficient and long- lasting inhibition of Gq/11 signaling has been attributed solely to a wedge- like binding to G alpha, thereby preventing separation of the GTPase and alpha- helical domains and thus GDP release. Here, we use X- ray crystallography, biochemical and signaling assays, and BRET- based biosensors to show that FR and YM also function as stabilizers of the G alpha:Gfa gamma subunit interface. Our high- resolution structures reveal a network of residues in G alpha and two highly conserved amino acids in Gfa that are targeted by FR and YM to glue the Gfa gamma complex to the inactive G alpha GDP subunit. Unlike all previously developed nucleotide- state specific inhibitors that sequester G alpha in its OFF- state but compete with Gfa gamma, FR and YM actively promote the inhibitory occlusion of G alpha GDP by Gfa gamma. In doing so, they securely lock the entire heterotrimer, not just G alpha, in its inactive state. Our results identify FR and YM as molecular glues for G alpha and Gfa gamma that combine simultaneous binding to both subunits with inhibition of G protein signaling.