title: Isolation of a deoxycytidylate methyl transferase capable of protecting DNA uniquely against cleavage by endonuclease R.Aqu I (isoschizomer of Ava I).
abstract: A sequence-specific modification methylase (M.AquI) was isolated and purified from Agmenellum quadruplicatum (Synechococcus PCC 7002). This enzyme uniquely methylates the deoxycytidylate residue in the sequence *CYCGRG indicated by the asterisk. It was shown to protect DNA against cleavage by restriction endonucleases AvaI, SmaI and XhoI, which recognize the sequences CYCGRG, CCCGGG, and CTCGAG, respectively.
mesh_terms: D001483:Base Sequence; D000458:Cyanobacteria / Q000201:enzymology* / Q000235:genetics; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000302:isolation & purification*; D004262:DNA Restriction Enzymes / Q000378:metabolism*; D015257:DNA-Cytosine Methylases; D015252:Deoxyribonucleases, Type II Site-Specific; D013379:Substrate Specificity
chemical_list: C049759:DNA modification methylase M.AquI; D015257:DNA-Cytosine Methylases; D004248:DNA (Cytosine-5-)-Methyltransferases; D004262:DNA Restriction Enzymes; C028678:CYCGRG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific