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Crystal structure of the GDP-bound human M-RAS protein in two crystal forms

Stephanie M Bester1, Rebecca Abrahamsen1, Luiza Rodrigues Samora1

  • 1Pfizer Boulder Research and Development, 3200 Walnut Street, Boulder, CO 80301, USA.

Acta Crystallographica. Section F, Structural Biology Communications
|August 28, 2024
PubMed

Insights

The crystal structure of inactive human M-RAS protein was determined, revealing unique packing not seen in mouse M-RAS. This inactive structure provides new insights for developing targeted M-RAS therapies.

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Biochemistry

Background:

  • M-RAS is a key regulator in the RAF-MEK signaling pathway, essential for cell proliferation and differentiation.
  • Activation of M-RAS by GTP leads to complex formation with SHOC2 and PP1C, driving downstream signal transduction.
  • Understanding M-RAS structure is crucial for developing targeted therapies against diseases involving this pathway.

Purpose of the Study:

  • To determine the crystal structure of the GDP-bound human M-RAS protein.
  • To analyze the crystal packing of the full-length and truncated human M-RAS structures.
  • To compare the human M-RAS structure with existing mouse M-RAS structures and AlphaFold2 predictions.

Main Methods:

  • X-ray crystallography was employed to obtain the crystal structures of human M-RAS.
  • Structural alignment and root-mean-square deviation (r.m.s.d.) analysis were performed to compare structures.
  • Bioinformatics tools, including AlphaFold2, were used for structure prediction and comparison.

Main Results:

  • The crystal structure of GDP-bound human M-RAS was successfully determined, showing two distinct crystal packing forms.
  • Both full-length and truncated human M-RAS structures showed high agreement with AlphaFold2 predictions, except for the Switch regions.
  • Unique crystal packing was observed in the full-length human M-RAS structure, differing from the mouse M-RAS structure despite high sequence similarity.

Conclusions:

  • The determined inactive human M-RAS structure offers valuable insights into its conformational states.
  • The unique crystal packing provides a basis for understanding M-RAS interactions and regulation.
  • This structural information can guide the rational design of selective small-molecule inhibitors targeting M-RAS for therapeutic purposes.
Keywords:
GDPGTPase structureM-RAScrystal packing

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