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Reduced DNA flexibility in complexes with a type II DNA binding protein
- Source :
- Biochemistry. 29:959-965
- Publication Year :
- 1990
- Publisher :
- American Chemical Society (ACS), 1990.
-
Abstract
- We studied internal molecular motions in Bacillus subtilis phage SPO1 DNA using the time-resolved fluorescence polarization anisotropy (FPA) of intercalated ethidium. The torsional flexibility of this (hydroxymethyl)uracil-containing DNA is very similar to that of naturally occurring thymine-containing DNAs, as judged from fits of the time-resolved FPA decay to an elastic DNA model. Binding of transcription factor 1 (TF1), a type II procaryotic DNA binding protein encoded by the phage SPO1, enhances the FPA, indicating a substantial decrease in the average DNA torsional flexibility in the DNA-TF1 complex. The FPA increase is correlated with a reduced ethidium binding affinity. The effects can be noticed at TF1 binding ratios less than 1 TF1 dimer/500 DNA base pairs, and the measured torsional rigidity at high TF1 binding ratios (1 TF1 dimer/15-20 DNA base pairs) is about 7 times greater than in the absence of TF1. On the basis of a discussion of various mechanisms for the observed effect we argue that it is due to protein-induced DNA bending at low binding densities although other explanations are also possible. This interpretation might have implications for understanding the biological function of TF1.
- Subjects :
- DNA clamp
Molecular Structure
HMG-box
Base pair
Dimer
Fluorescence Polarization
DNA-binding domain
Biology
Biochemistry
Molecular biology
Single-stranded binding protein
DNA-Binding Proteins
Pentoxyl
Viral Proteins
chemistry.chemical_compound
chemistry
Ethidium
DNA, Viral
Biophysics
biology.protein
Nucleic Acid Conformation
Bacteriophages
Protein–DNA interaction
DNA
Subjects
Details
- ISSN :
- 15204995 and 00062960
- Volume :
- 29
- Database :
- OpenAIRE
- Journal :
- Biochemistry
- Accession number :
- edsair.doi.dedup.....65d6e9ed00b2bbf1c2dbed23005f274d