The type II restriction endonuclease MvaI has dual specificity.
The MvaI restriction endonuclease cuts 5'-CC↓AGG-3'/5'-CC↑TGG-3' sites as indicated by the arrows. N4-methylation of the inner cytosines (C(m4)CAGG/C(m4)CTGG) protects the site against MvaI cleavage. Here, we show that MvaI nicks the G-strand of the related sequence (CCGGG/CCCGG, BcnI site) if the inner cytosines are C5-methylated: C(m5)C↓GGG/CC(m5)CGG. At M.SssI-methylated SmaI sites, where two oppositely oriented methylated BcnI sites partially overlap, double-nicking leads to double-strand cleavage (CC(m5)C↓GGG/CC(m5)C↑GGG) generating fragments with blunt ends. The double-strand cleavage rate and the stringency of substrate site recognition is lower at the methylation-dependent site than at the canonical target site. MvaI is the first restriction endonuclease shown to possess, besides the 'normal' activity on its unmethylated recognition site, also a methylation-directed activity on a different sequence.
Stier
Ildikó
I
Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, 6726 Szeged, Temesvári krt. 62, Hungary.
Kiss
Antal
A
D053837:DNA Cleavage; D015257:DNA-Cytosine Methylases / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism*; D013379:Substrate Specificity
C081573:DNA modification methylase SssI; D015257:DNA-Cytosine Methylases; C025651:CCCGGG-specific type II deoxyribonucleases; C035801:CCSGG-specific type II deoxyribonucleases; C046545:CCWGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific