Arginine-55 in the beta-arm is essential for the activity of DNA-binding protein HU from Bacillus stearothermophilus.
DNA-binding protein HU (BstHU) from Bacillus stearothermophilus is a homodimeric protein which binds to DNA in a sequence-nonspecific manner. In order to identify the Arg residues essential for DNA binding, four Arg residues (Arg-53, Arg-55, Arg-58, and Arg-61) within the beta-arm structure were replaced either by Gln, Lys, or Glu residues, and the resulting mutants were characterized with respect to their DNA-binding activity by a filter-binding analysis and surface plasmon resonance analysis. The results indicate that three Arg residues (Arg-55, Arg-58, and Arg-61) play a crucial role in DNA binding as positively charged recognition groups in the order of Arg-55 > Arg-58 > Arg-61 and that these are required to decrease the dissociation rate constant for BstHU-DNA interaction. In contrast, the Arg-53 residue was found to make no contribution to the binding activity of BstHU.
Saitoh
F
F
Laboratory of Biochemistry, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Kawamura
S
S
Yamasaki
N
N
Tanaka
I
I
Kimura
M
M
D001120:Arginine / Q000502:physiology*; D001426:Bacterial Proteins / Q000737:chemistry*; D015374:Biosensing Techniques; D004268:DNA-Binding Proteins / Q000737:chemistry*; D019281:Dimerization; D001411:Geobacillus stearothermophilus / Q000737:chemistry*; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; C040330:histone-like protein HU, bacteria; D001120:Arginine