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Interaction of nucleolar phosphoprotein B23 with nucleic acids
T S Dumbar1, G A Gentry, M O Olson
1Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4505.
Biochemistry
|November 28, 1989
Summary
Nucleolar phosphoprotein B23 preferentially binds single-stranded nucleic acids with high affinity and cooperativity. This protein exhibits helix-destabilizing activity, potentially crucial for its role in ribosome assembly.
Area of Science:
- Molecular Biology
- Biochemistry
Background:
- Nucleolar phosphoprotein B23 is involved in ribosome biogenesis.
- Understanding its nucleic acid interactions is key to elucidating its function.
Purpose of the Study:
- To investigate the nucleic acid binding properties of eukaryotic nucleolar phosphoprotein B23.
- To characterize the affinity, specificity, and functional activity of protein B23's nucleic acid interactions.
Main Methods:
- Gel retardation and filter binding assays to assess nucleic acid binding.
- Fluorescence techniques and circular dichroism (CD) to study binding dynamics and structural changes.
- Utilized a novel purification procedure for native protein B23.
Main Results:
- Protein B23 demonstrated a strong preference for single-stranded nucleic acids over double-stranded forms.
- Equilibrium binding studies revealed cooperative binding with a high affinity (K omega = 5 x 10(7) M-1) and a binding site size of 11 nucleotides.
- Circular dichroism indicated that protein B23 possesses helix-destabilizing activity on single-stranded RNA (poly(rA), poly(rC)) but not double-stranded DNA.
Conclusions:
- Protein B23 exhibits high-affinity, cooperative binding to single-stranded nucleic acids.
- The identified helix-destabilizing activity suggests a role in managing nucleic acid structures during ribosome assembly.