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Cloning of a 3-methyladenine-DNA glycosylase from Arabidopsis thaliana.

ABSTRACT: We have isolated an Arabidopsis thaliana cDNA that complements the methyl methanesulfonate-sensitive phenotype of an Escherichia coli double mutant deficient in 3-methyladenine glycosylases (DNA-3-methyladenine glycosidases I and II, EC 3.2.2.20 and 3.2.2.21, respectively, encoded by tag and alkA). Expression of the Arabidopsis cDNA enhances the methyl methanesulfonate resistance of the E. coli double mutant by nearly four orders of magnitude. The cDNA corresponds to a single-copy, nuclearly encoded sequence which specifies a predicted 28.1-kDa protein with a charge of +8 at pH 7.0. Enzymatic analysis of extracts prepared from the transformed mutants indicates that the cDNA encodes a 3-methyladenine glycosylase. The predicted amino acid sequence of the Arabidopsis glycosylase has significant homology to other eukaryotic 3-methyladenine glycosylases.

SUBMITTER: Santerre A

PROVIDER: S-EPMC43346 | biostudies-other | 1994 Mar

REPOSITORIES: biostudies-other

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Cloning of a 3-methyladenine-DNA glycosylase from Arabidopsis thaliana.

Santerre A A Britt A B AB

Proceedings of the National Academy of Sciences of the United States of America 19940301 6

We have isolated an Arabidopsis thaliana cDNA that complements the methyl methanesulfonate-sensitive phenotype of an Escherichia coli double mutant deficient in 3-methyladenine glycosylases (DNA-3-methyladenine glycosidases I and II, EC 3.2.2.20 and 3.2.2.21, respectively, encoded by tag and alkA). Expression of the Arabidopsis cDNA enhances the methyl methanesulfonate resistance of the E. coli double mutant by nearly four orders of magnitude. The cDNA corresponds to a single-copy, nuclearly enc ...[more]

PMID: 8134381

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Project description:BACKGROUND:The emergence of artemisinin-resistant malaria parasites highlights the need for novel drugs and their targets. Alkylation of purine bases can hinder DNA replication and if unresolved would eventually result in cell death. DNA-3-methyladenine glycosylase (MAG) is responsible for the repair of those alkylated bases. Plasmodium falciparum (Pf) MAG was characterized for its potential for development as an anti-malarial candidate. METHODS:Native PfMAG from crude extract of chloroquine- and pyrimethamine-resistant P. falciparum K1 strain was partially purified using three chromatographic procedures. From bio-informatics analysis, primers were designed for amplification, insertion into pBAD202/D-TOPO and heterologous expression in Escherichia coli of recombinant PfMAG. Functional and biochemical properties of the recombinant enzyme were characterized. RESULTS:PfMAG activity was most prominent in parasite schizont stages, with a specific activity of 147 U/mg (partially purified) protein. K1 PfMAG contained an insertion of AAT (coding for asparagine) compared to 3D7 strain and 16% similarity to the human enzyme. Recombinant PfMAG (74 kDa) was twice as large as the human enzyme, preferred double-stranded DNA substrate, and demonstrated glycosylase activity over a pH range of 4-9, optimal salt concentration of 100-200 mM NaCl but reduced activity at 250 mM NaCl, no requirement for divalent cations, which were inhibitory in a dose-dependent manner. CONCLUSION:PfMAG activity increased with parasite development being highest in the schizont stages. K1 PfMAG contained an indel AAT (asparagine) not present in 3D7 strain and the recombinant enzyme was twice as large as the human enzyme. Recombinant PfMAG had a wide range of optimal pH activity, and was inhibited at high (250 mM) NaCl concentration as well as by divalent cations. The properties of PfMAG provide basic data that should be of assistance in developing anti-malarials against this potential parasite target.

Dataset Information

Cloning of a 3-methyladenine-DNA glycosylase from Arabidopsis thaliana.

Publications

Cloning of a 3-methyladenine-DNA glycosylase from Arabidopsis thaliana.

Similar Datasets

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