EcoRI recognizes the six-base DNA sequence GAATTC.
EcoRI is a restriction endonuclease isolated from the bacterium Escherichia coli. It cuts within the palindromic sequence 5′-GAATTC-3′, cleaving the two DNA strands at defined positions and producing staggered, or sticky, ends with short single-stranded overhangs.
Those predictable ends made EcoRI a foundational tool in recombinant-DNA research. DNA fragments cut with compatible ends can be joined by DNA ligase, allowing scientists to construct plasmids and other engineered molecules.
The name follows a bacterial naming system: “Eco” refers to E. coli, while the remaining letters and Roman numeral distinguish the enzyme’s source strain and discovery order. EcoRI should not be confused with DNA methylases, which protect particular sites by modifying bases rather than cutting the backbone.