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Matsumoto Y , Kim K , Katz DS , Feng JA
Catalytic center of DNA polymerase beta for excision of deoxyribose phosphate groups
Biochemistry. 1998 May 5;37(18) :6456-6464
PMID: ISI:000073585600029   
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The amino-terminal 8-kDa domain of vertebrate DNA polymerase beta (pol beta) has an activity to excise deoxyribose phosphate (dRP) groups' from 5'-incised apurinic/apyrimidinic (AP) sites during base excision repair. The excision reaction proceeds via a beta-elimination reaction following formation of a Schiff base between an aldehyde group of the AP site and an amino group of the enzyme. Here we report that the Lys-72 residue of this enzyme is the catalytic center for dRP excision. Substitutions of Lys-72 with Arg or Gin reduced the dRP excision activity to less than 1% of the wild-type 8-kDa domain, while substitutions of Lys-35, Lys-68, or Lys-84 did not abolish its activity. The Lys-72 mutations also significantly decreased Schiff base intermediates trapped by reduction with sodium borohydride, The 8-kDa domain alone was able to bind preferentially to a single-nucleotide gap or 5'- incised synthetic AP site on double-stranded DNA. The Lys-72 mutations did not affect this damage-specific DNA binding activity. When introduced into the intact enzyme, a mutation of Lys-72 to Arg did not affect DNA synthesis activity of pol beta, but eliminated the repair activity. Addition of the wild- type 8-kDa domain to this reaction restored the repair activity. These results indicate a specific role of Lys-72 of pol beta in the dRP excision during base excision repair.
Times Cited: 29 English Article ZM880 BIOCHEMISTRY-USA