Compact form of DNA induced by DNA-binding protein HU.
Interaction of DNA-binding protein HU from Bacillus stearothermophilus (HUBst) with coliphage T2 DNA was investigated by means of a single-duplex DNA chain visualization method using fluorescence microscopy. Fluorescence microscopic images of coliphage T2 DNA molecules were observed as a function of HUBst concentration. The average fluorescence image size of T2 DNA decreased with increase in HUBst concentration to a size comparable to that of a DNA globule induced by polyethylene glycol (PEG) and multivalent cation (MVC). The change to globule-like DNA proceeded gradually and monotonously, in contrast to the coil-globule transition of DNA induced by PEG and MVC. The histogram of the fluorescence image length was essentially a single-modal one throughout the process of conformational change. These results indicate that the process of shrinking of DNA from a random coil to a globule-like one is not of a transitional nature. The interaction of HUBst with DNA and the mechanism of shrinkage are concluded to be different from those of PEG-induced and MVC-induced coil-globule transition of DNA.
Endo
Takashi
T
Division of Biological Sciences, Graduate School of Science, Hokkaido University, Kita-ku, Sapporo 060-0810, Japan.
Sasaki
Naoki
N
Tanaka
Isao
I
Nakata
Mitsuo
M
D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology*; D017122:Bacteriophage T4 / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D004396:Coloring Agents / Q000494:pharmacology; D004247:DNA / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D001411:Geobacillus stearothermophilus / Q000737:chemistry; D008856:Microscopy, Fluorescence; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D013997:Time Factors
D001426:Bacterial Proteins; D004396:Coloring Agents; D004268:DNA-Binding Proteins; C040330:histone-like protein HU, bacteria; D004247:DNA