The G Protein Inhibitor YM-254890 is an Allosteric Glue.

Area of Science:

• Biochemistry
• Pharmacology
• Molecular Biology

Background:

• G protein-coupled receptors (GPCRs) are crucial drug targets.
• Targeting G proteins, downstream effectors of GPCRs, offers an alternative therapeutic strategy.
• The natural product YM-254890 inhibits Gq/11, highlighting the potential of G protein-specific inhibitors.

Purpose of the Study:

• To elucidate the inhibitory mechanism of YM-254890 on G proteins.
• To investigate the role of conformational dynamics in G protein isoform selectivity.
• To guide the development of novel, highly specific G protein inhibitors.

Main Methods:

• Molecular dynamics simulations of G protein isoforms (Gα subunits and Gαβγ heterotrimers).
• Construction and analysis of Markov state models (MSMs) to characterize conformational landscapes.
• Computational analysis of YM-254890 binding and allosteric effects.

Main Results:

• YM-sensitive Gα subunits exhibit a higher propensity for YM-bound conformations compared to insensitive isoforms.
• Significant allosteric coupling exists between the YM and Gβγ-binding sites on Gα.
• Gβγ binding enhances the preorganization of Gα for YM binding, demonstrating positive cooperativity.

Conclusions:

• YM-254890 functions as an 'allosteric glue,' stabilizing the Gα-Gβγ complex.
• Conformational differences and allosteric mechanisms dictate G protein isoform selectivity for YM.
• These findings provide a mechanistic basis for designing future G protein-targeted therapeutics.