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Structural consequences of a cancer-causing BRCA1-BRCT missense mutation
R Scott Williams1, J N Mark Glover
1Department of Biochemistry, 437 Medical Sciences Building, University of Alberta, Edmonton T6G 2H7, Canada.
The Journal of Biological Chemistry
|November 13, 2002
Summary
A BRCA1 mutation (Met-1775 --> Arg-1775) destabilizes the BRCT domain, leading to unfolding and impaired tumor suppressor function. This structural change explains defects in BRCA1-M1775R protein activity.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- The carboxyl-terminal BRCT repeat region of BRCA1 is essential for its tumor suppressor function.
- The molecular mechanisms by which BRCA1 BRCT missense mutations impact function are not fully understood.
Purpose of the Study:
- To investigate the structural consequences of a specific cancer-associated BRCA1 BRCT missense mutation (Met-1775 --> Arg-1775).
- To elucidate how this mutation affects the stability and function of the BRCA1 BRCT tandem repeat domain.
Main Methods:
- Structural analysis of the mutated BRCT tandem repeat domain (BRCT-M1775R).
- Assessment of the impact of the Met-1775 --> Arg-1775 substitution on protein structure and stability.
Main Results:
- The Met-1775 --> Arg-1775 substitution causes the mutated side chain to be extruded from the protein's hydrophobic core, altering the surface.
- Conformational instability of BRCT-M1775R arises from charge-charge repulsion, hydrophobic core rearrangement, and disrupted hydrogen bonding.
- The mutated BRCT domain undergoes destabilization and global unfolding at physiological temperatures.
Conclusions:
- The structural destabilization and unfolding of the BRCA1 BRCT domain due to the M1775R mutation explain the observed molecular and genetic defects.
- Understanding these structural changes is crucial for comprehending BRCA1-related cancers and developing targeted therapies.