title: Structural mechanisms for the 5'-CCWGG sequence recognition by the N- and C-terminal domains of EcoRII.
abstract: EcoRII restriction endonuclease is specific for the 5'-CCWGG sequence (W stands for A or T); however, it shows no activity on a single recognition site. To activate cleavage it requires binding of an additional target site as an allosteric effector. EcoRII dimer consists of three structural units: a central catalytic core, made from two copies of the C-terminal domain (EcoRII-C), and two N-terminal effector DNA binding domains (EcoRII-N). Here, we report DNA-bound EcoRII-N and EcoRII-C structures, which show that EcoRII combines two radically different structural mechanisms to interact with the effector and substrate DNA. The catalytic EcoRII-C dimer flips out the central T:A base pair and makes symmetric interactions with the CC:GG half-sites. The EcoRII-N effector domain monomer binds to the target site asymmetrically in a single defined orientation which is determined by specific hydrogen bonding and van der Waals interactions with the central T:A pair in the major groove. The EcoRII-N mode of the target site recognition is shared by the large class of higher plant transcription factors of the B3 superfamily.
authors.affiliation: Institute of Biotechnology, Graiciuno 8, LT-02241 Vilnius, Lithuania.
authors.forename: Dmitrij
authors.initials: D
authors.lastname: Golovenko
authors.forename: Elena
authors.initials: E
authors.lastname: Manakova
authors.forename: Giedre
authors.initials: G
authors.lastname: Tamulaitiene
authors.forename: Saulius
authors.initials: S
authors.lastname: Grazulis
authors.forename: Virginijus
authors.initials: V
authors.lastname: Siksnys
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D019175:DNA Methylation; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry*; D008958:Models, Molecular; D017434:Protein Structure, Tertiary
chemical_list: D004247:DNA; C046545:CCWGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific