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Functional analysis of an acid adaptive DNA adenine methyltransferase from Helicobacter pylori 26695.

ABSTRACT: HP0593 DNA-(N(6)-adenine)-methyltransferase (HP0593 MTase) is a member of a Type III restriction-modification system in Helicobacter pylori strain 26695. HP0593 MTase has been cloned, overexpressed and purified heterologously in Escherichia coli. The recognition sequence of the purified MTase was determined as 5'-GCAG-3'and the site of methylation was found to be adenine. The activity of HP0593 MTase was found to be optimal at pH 5.5. This is a unique property in context of natural adaptation of H. pylori in its acidic niche. Dot-blot assay using antibodies that react specifically with DNA containing m6A modification confirmed that HP0593 MTase is an adenine-specific MTase. HP0593 MTase occurred as both monomer and dimer in solution as determined by gel-filtration chromatography and chemical-crosslinking studies. The nonlinear dependence of methylation activity on enzyme concentration indicated that more than one molecule of enzyme was required for its activity. Analysis of initial velocity with AdoMet as a substrate showed that two molecules of AdoMet bind to HP0593 MTase, which is the first example in case of Type III MTases. Interestingly, metal ion cofactors such as Co(2+), Mn(2+), and also Mg(2+) stimulated the HP0593 MTase activity. Preincubation and isotope partitioning analyses clearly indicated that HP0593 MTase-DNA complex is catalytically competent, and suggested that DNA binds to the MTase first followed by AdoMet. HP0593 MTase shows a distributive mechanism of methylation on DNA having more than one recognition site. Considering the occurrence of GCAG sequence in the potential promoter regions of physiologically important genes in H. pylori, our results provide impetus for exploring the role of this DNA MTase in the cellular processes of H. pylori.

SUBMITTER: Banerjee A

PROVIDER: S-EPMC3036652 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature

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Functional analysis of an acid adaptive DNA adenine methyltransferase from Helicobacter pylori 26695.

Banerjee Arun A Rao Desirazu N DN

PloS one 20110209 2

HP0593 DNA-(N(6)-adenine)-methyltransferase (HP0593 MTase) is a member of a Type III restriction-modification system in Helicobacter pylori strain 26695. HP0593 MTase has been cloned, overexpressed and purified heterologously in Escherichia coli. The recognition sequence of the purified MTase was determined as 5'-GCAG-3'and the site of methylation was found to be adenine. The activity of HP0593 MTase was found to be optimal at pH 5.5. This is a unique property in context of natural adaptation of ...[more]

PMID: 21347417

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Project description:Dear Sir or Madam, we report an in-depth proteogenomics study of Helicobacter pylori strain 26695 and provide the supporting MS data via ProteomExchange. The study includes 2 biological replicates with 6 different datasets: G1: in-gel digestion with trypsin, replicate 1 G2: in-gel digestion with trypsin, replicate 2 T1: SEC fractionation of low molecular weight (LMW) proteins and subsequent trypsin digestion, replicate 1 T2: SEC fractionation of LMW proteins and subsequent trypsin digestion, replicate 2 A1: SEC fractionation of LMW proteins and subsequent AspN digestion, replicate 1 A2: SEC fractionation of LMW proteins and subsequent AspN digestion, replicate 2 L1: SEC fractionation of LMW proteins and subsequent LysC digestion, replicate 1 L2: SEC fractionation of LMW proteins and subsequent LysC digestion, replicate 2 In our proteogenomics approach, we could identify four previously missing protein annotations and were able to correct sequences of six protein coding regions. Furthermore we identified signal peptidase cleavage sites for 72 different proteins. MGFs were generated by Maxquant 1.1 [1] using recalibration of peptide parent masses. For PRIDE (http://www.ebi.ac.uk/pride) submission, we made an additional database search with Mascot and X!Tandem using the SearchGUI [2]. Therefore we searched against a NCBI database of H. pylori strain 26695 complemented with the sequence corrections, signal peptide cleavage sites and missing annotations with the same configurations as described in materials and methods. For pride xml export we used the software PeptideShaker (http://code.google.com/p/peptide-shaker/). The complemented database has entries which will be submitted to the UniProtKB via SPIN. The entries have the according SPIN number as accession number. The NCBI accession numbers for the shortened sequences due to signal peptide cleavage are extended with “_1”. The fasta database is added to the submission. For additional information, please contact me: stephan.mueller@ufz.de Yours sincerely, Stephan Mueller References: [1] Cox J, Neuhauser N, Michalski A, Scheltema RA, Olsen JV, Mann M. Andromeda: a peptide search engine integrated into the MaxQuant environment. Journal of proteome research. 2011;10:1794-805. [2] Vaudel M, Barsnes H, Berven FS, Sickmann A, Martens L. SearchGUI: An open-source graphical user interface for simultaneous OMSSA and X!Tandem searches. Proteomics. 2011;11:996-9.

Dataset Information

Functional analysis of an acid adaptive DNA adenine methyltransferase from Helicobacter pylori 26695.

Publications

Functional analysis of an acid adaptive DNA adenine methyltransferase from Helicobacter pylori 26695.

Similar Datasets

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