Site-directed mutagenesis of glutamic acid 172 to glutamine completely inactivated human O6-alkylguanine-DNA-alkyltransferase.
AuthorsRafferty, Joseph A
Elder, Rhoderick H
Margison, Geoffrey P
Douglas, K T
AffiliationCRC Department of Carcinogenesis, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Manchester, U.K.
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AbstractDNA repair by O6-alkylguanine-DNA-alkyltransferase involves the stoichiometric transfer of the O6-alkyl group from the guanine lesion to the active-site cysteine residues of the protein. Site-directed mutagenesis of glutamic acid 172 of human O6-alkylguanine-DNA-alkyltransferase (EC 18.104.22.168) to glutamine totally abolished the alkyltransferase activity of the protein. This suggests that glutamic acid 172 is crucial to the alkyl transfer. It may act as a general acid (as CO2H) or base (as CO2-), or have a role as a component of a salt-link (-CO2-.....+N-), vital for the structural integrity of the active site. This is the first mutational inactivation of a protein in this family of DNA repair molecules by means of a residue change outside the highly conserved pentet (PCHRV) which includes the active-site cysteine.
CitationSite-directed mutagenesis of glutamic acid 172 to glutamine completely inactivated human O6-alkylguanine-DNA-alkyltransferase. 1994, 199 (1):285-91 Biochem. Biophys. Res. Commun.
JournalBiochemical and Biophysical Research Communications
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