Open AccessIsolation, characterization and baculovirus-mediated expression of the cDNA encoding cytosine DNA methyltransferase from Pisum sativum
Author(s) -
Sriharsa Pradhan,
Michele Cummings,
Richard J. Roberts,
R. L. P. Adams
Publication year - 1998
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/26.5.1214
Subject(s) - biology , complementary dna , arabidopsis , microbiology and biotechnology , open reading frame , nucleic acid sequence , dna , dna methyltransferase , gene , methyltransferase , genetics , peptide sequence , methylation , mutant
A series of overlapping clones complementary to the Arabidopsis cytosine-5 DNA methyltransferase (C-5 MTase) has been isolated from pea cDNA libraries. The assembled nucleic acid sequence contains an open reading frame of 4761 bp encoding a protein of 1554 amino acids. Like other eukaryotic C-5 MTases, the inferred protein has a presumed regulatory N-terminal region linked to a catalytic C-terminal domain, which has eight of the ten conserved motifs found in prokaryotic C-5 MTases. The pea C-5 MTase has 65% identity at the nucleotide level and 61% identity at the protein level, with the Arabidopsis C-5 MTase. The catalytic domain of the pea enzyme shares 78% identity with Arabidopsis and approximately 52% identity with murine and human C-5 MTases, including the relative position of the proline-cysteine dipeptides of the catalytic centre. Using the conserved region of the cDNA as a probe, we have identified a transcript of 5 kb. Southern blot analysis of pea genomic DNA with the above probe indicates the presence of a single gene. Using poly(A)+ RNA from different developmental stages and different tissues, we have observed that expression is confined mostly to the rapidly dividing tissues of the plant. Expression of this assembled cDNA in a baculovirus system gives a protein of approximately 174 kDa. The expressed protein can be cross-linked, in an AdoMet-dependent manner, to duplex oligonucleotide substrates containing FdC in place of target cytosines in either CG or CAG/CTG sequences.