title: Creation of a fully functional human chimeric DNA repair protein. Combining O6-methylguanine DNA methyltransferase (MGMT) and AP endonuclease (APE/redox effector factor 1 (Ref 1)) DNA repair proteins.
abstract: A dose-limiting toxicity of certain chemotherapeutic alkylating agents is their toxic effects on nontarget tissues such as the bone marrow. To overcome the myelosuppression observed by chemotherapeutic alkylating agents, one approach is to increase the level of DNA repair proteins in hematopoietic stem and progenitor cells. Toward this goal, we have constructed a human fusion protein consisting of O6-methylguanine DNA methyltransferase coupled with an apurinic endonuclease, resulting in a fully functional protein for both O6-methylguanine and apurinic/apyrimidinic (AP) site repair as determined by biochemical analysis. The chimeric protein protected AP endonuclease-deficient Escherichia coli cells against methyl methanesulfonate and hydrogen peroxide (H2O2) damage. A retroviral construct expressing the chimeric protein also protected HeLa cells against 1,3-bis(2-chloroethyl)-1-nitrosourea and methyl methanesulfonate cytotoxicity either when these agents were used separately or in combination. Moreover, as predicted from previous analysis, truncating the amino 150 amino acids of the apurinic endonuclease portion of the O6-methylguanine DNA methyltransferase-apurinic endonuclease protein resulted in the retention of O6-methylguanine DNA methyltransferase activity but loss of all AP endonuclease activity. These results demonstrate that the fusion of O6-methylguanine DNA methyltransferase and apurinic endonuclease proteins into a combined single repair protein can result in a fully functional protein retaining the repair activities of the individual repair proteins. These and other related constructs may be useful for protection of sensitive tissues and, therefore, are candidate constructs to be tested in preclinical models of chemotherapy toxicity.
authors.affiliation: Department of Pediatrics,Wells Center for Pediatric Research, Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA.
authors.forename: W K
authors.initials: WK
authors.lastname: Hansen
authors.forename: W A
authors.initials: WA
authors.lastname: Deutsch
authors.forename: A
authors.initials: A
authors.lastname: Yacoub
authors.forename: Y
authors.initials: Y
authors.lastname: Xu
authors.forename: D A
authors.initials: DA
authors.lastname: Williams
authors.forename: M R
authors.initials: MR
authors.lastname: Kelley
mesh_terms: D000970:Antineoplastic Agents / Q000009:adverse effects; D019757:Carbon-Oxygen Lyases / Q000235:genetics*; D003001:Cloning, Molecular; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D006367:HeLa Cells; D006801:Humans; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics*
chemical_list: D000970:Antineoplastic Agents; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D019853:O(6)-Methylguanine-DNA Methyltransferase; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; D019757:Carbon-Oxygen Lyases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase