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Sequential metal binding by the RING finger domain of BRCA1
1Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205, USA.
Biochemistry
|August 19, 1997
Summary
The BRCA1 RING finger domain binds metal ions sequentially, with site 1 binding before site 2. This metal binding influences the protein
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- The BRCA1 gene is crucial for familial breast and ovarian cancer susceptibility.
- BRCA1 contains an amino-terminal RING finger domain, a known zinc-binding motif.
- RING finger domains typically feature two interleaved metal-binding sites.
Purpose of the Study:
- To characterize the metal binding properties of the BRCA1 RING finger domain.
- To investigate the metal-dependent folding of BRCA1 RING finger peptides.
- To understand the structural implications of metal ion coordination.
Main Methods:
- Spectroscopic analysis using cobalt(II) as a probe.
- Thermodynamic analysis of metal binding.
- Circular dichroism spectroscopy to assess protein structure.
- Studies on variant peptides to understand metal binding cooperativity.
Main Results:
- Metal binding to the BRCA1 RING finger is sequential, with site 1 (four-cysteine) binding preferentially before site 2 (three-cysteine, one-histidine).
- Metal binding is anticooperative, with dissociation constants indicating weaker binding to site 2 when site 1 is occupied.
- The BRCA1 RING finger peptide exhibits some structure in the absence of metal ions, which is further altered upon metal binding.
Conclusions:
- The BRCA1 RING finger domain's metal binding is a regulated, sequential process.
- Anticooperative metal binding influences the domain's stability and structure.
- Understanding these properties is essential for elucidating BRCA1's role in cancer susceptibility.