BRCT domain of DNA polymerase μ has DNA-binding activity and promotes the DNA polymerization activity.
DNA polymerase μ (pol μ) catalyzes nonhomologous end-joining in DNA double-stranded break repair. Pol μ consists of an amino-terminal BRCA1 carboxyl-terminal homology (BRCT) domain and a pol β-like region, which contains the catalytic site. By DNA cellulose column chromatography, using full-length pol μ and five different deletion mutants, we found that the amino-terminal region has double-stranded DNA (dsDNA)-binding activity. Pol μ without BRCT domain reduces the DNA polymerization activity when compared to full-length pol μ. Observation by atomic force microscopy showed that full-length pol μ binds to the ends and middle part of dsDNA. Pol μ lacking the amino-terminal region or with a mutation within the BRCT domain bound only to DNA ends, whereas the amino-terminal region with the BRCT domain bound to both the ends and the middle part of dsDNA (mpdDNA). Terminal deoxynucleotidyltransferase, which, like pol μ, belongs to the X family DNA polymerases, also bound to mpdDNA through its amino-terminal region.
Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, Japan.
Takuro
T
Matsumoto
Kaori
K
Go
Mariko
M
Hyodo
Kotaro
K
Koiwai
So
S
Maezawa
Takahide
T
Hayano
Masahiro
M
Suzuki
Osamu
O
Koiwai
D000595:Amino Acid Sequence; D020134:Catalytic Domain; D002845:Chromatography / Q000379:methods; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004253:DNA Nucleotidylexotransferase / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D015723:Gene Library; D015894:Genome, Human; D006801:Humans; D018625:Microscopy, Atomic Force; D009154:Mutation; D058105:Polymerization; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
D004268:DNA-Binding Proteins; D004247:DNA; C407743:DNA polymerase mu; D004253:DNA Nucleotidylexotransferase; D004259:DNA-Directed DNA Polymerase