Role of the N-terminal domain of the human DMC1 protein in octamer formation and DNA binding.
The DMC1 protein, a eukaryotic homologue of RecA that shares significant amino acid identity with RAD51, exhibits two oligomeric DNA binding forms, an octameric ring and a helical filament. In the crystal structure of the octameric ring form, the DMC1 N-terminal domain (1-81 amino acid residues) was highly flexible, with multiple conformations. On the other hand, the N-terminal domain of Rad51 makes specific interactions with the neighboring ATPase domain in the helical filament structure. To gain insights into the functional role of the N-terminal domain of DMC1, we prepared a deletion mutant, DMC1-(82-340), that lacks the N-terminal 81 amino acid residues from the human DMC1 protein. Analytical ultracentrifugation experiments revealed that, whereas full-length DMC1 forms a octamer, DMC1-(82-340) is a heptamer. Furthermore, DNA binding experiments showed that DMC1-(82-340) was completely defective in both single-stranded and double-stranded DNA binding activities. Therefore, the N-terminal domain of DMC1 is required for the formation of the octamer, which may support the proper DNA binding activity of the DMC1 protein.
Kinebuchi
Takashi
T
Protein Research Group, RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan.
Kagawa
Wataru
W
Kurumizaka
Hitoshi
H
Yokoyama
Shigeyuki
S
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D010446:Peptide Fragments; D004247:DNA; D000251:Adenosine Triphosphatases; C074556:DMC1 protein, human