The cavity in the hydrophobic core of Myb DNA-binding domain is reserved for DNA recognition and trans-activation.
The DNA-binding domain of Myb consists of three imperfect repeats, R1, R2 and R3, each containing a helix-turn-helix motif variation. Among these repeats, R2 has distinct characteristics with high thermal instability. The NMR structure analysis found a cavity inside the hydrophobic core of R2 but not in R1 or R3. Here, we show that R2 has slow conformational fluctuations, and that a cavity-filling mutation which stabilizes the R2 structure significantly reduces specific Myb DNA-binding activity and trans-activation. Structural observations of the free and DNA-complexed stages suggest that the implied inherent conformational flexibility of R2, associated with the presence of the cavity, could be important for DNA recognition by Myb.
Ogata
K
K
Tsukuba Life Science Center, Institute of Physical and Chemical Research (RIKEN), Ibaraki, Japan.
Kanei-Ishii
C
C
Sasaki
M
M
Hatanaka
H
H
Nagadoi
A
A
Enari
M
M
Nakamura
H
H
Nishimura
Y
Y
Ishii
S
S
Sarai
A
A
D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D019077:Helix-Turn-Helix Motifs; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D011487:Protein Conformation; D011489:Protein Denaturation; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000378:metabolism; D020598:Proto-Oncogene Proteins c-myb; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; D004247:DNA