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AtMSI4 and RbAp48 WD-40 repeat proteins bind metal ions
1Department of Biochemistry, University of Missouri-Columbia, 65211, USA.
Abstract:
The mammalian RbAp48 protein is the most extensively studied member of the conserved family of Msi1-like WD-40 repeat proteins, which are components of complexes involved in the assembly and modification of chromatin. We have isolated a plant homolog of RbAp48, AtMSI4. By metal affinity chromatography, zinc blotting and atomic absorption analysis, we demonstrate that purified recombinant RbAp48 and AtMSI4 proteins bind 3-4 metal ions per molecule of protein. Metal competition assays indicate a preference for zinc. Both N- and C-terminal halves of RbAp48 and AtMSI4 display zinc binding activity, suggesting it is an intrinsic property of the propeller structures likely to be formed by these proteins. Metal binding might mediate and/or regulate protein-protein interactions which are functionally important in chromatin metabolism.
Insights
Mammalian RbAp48 and its plant homolog AtMSI4 bind zinc. This metal binding is an intrinsic property of these chromatin-associated proteins and may regulate their interactions.
Area of Science:
- Molecular Biology
- Plant Biology
- Biochemistry
Background:
- RbAp48 is a key protein in chromatin assembly and modification.
- RbAp48 belongs to the Msi1-like WD-40 repeat protein family.
- A plant homolog, AtMSI4, was identified.
Purpose of the Study:
- To investigate the metal-binding properties of RbAp48 and AtMSI4.
- To determine the metal preference and binding sites of these proteins.
- To explore the functional implications of metal binding in chromatin metabolism.
Main Methods:
- Metal affinity chromatography
- Zinc blotting
- Atomic absorption analysis
- Metal competition assays
Main Results:
- Purified recombinant RbAp48 and AtMSI4 bind 3-4 metal ions per molecule.
- These proteins show a preference for zinc binding.
- Both N- and C-terminal regions of the proteins exhibit zinc-binding activity.
- Metal binding appears to be an intrinsic property of their WD-40 repeat structures.
Conclusions:
- RbAp48 and AtMSI4 possess intrinsic zinc-binding capabilities.
- Metal binding may play a regulatory role in protein-protein interactions.
- These interactions are crucial for chromatin metabolism.