title: Structures of the rare-cutting restriction endonuclease NotI reveal a unique metal binding fold involved in DNA binding.
abstract: The structure of the rare-cutting restriction endonuclease NotI, which recognizes the 8 bp target 5'-GCGGCCGC-3', has been solved with and without bound DNA. Because of its specificity (recognizing a site that occurs once per 65 kb), NotI is used to generate large genomic fragments and to map DNA methylation status. NotI contains a unique metal binding fold, found in a variety of putative endonucleases, occupied by an iron atom coordinated within a tetrahedral Cys4 motif. This domain positions nearby protein elements for DNA recognition, and serves a structural role. While recognition of the central six base pairs of the target is accomplished via a saturated hydrogen bond network typical of restriction enzymes, the most peripheral base pairs are engaged in a single direct contact in the major groove, reflecting reduced pressure to recognize those positions. NotI may represent an evolutionary intermediate between mobile endonucleases (which recognize longer target sites) and canonical restriction endonucleases.
authors.affiliation: Graduate Program in Biomolecular Structure and Design, University of Washington, Seattle, WA 98195, USA.
authors.forename: Abigail R
authors.initials: AR
authors.lastname: Lambert
authors.forename: Django
authors.initials: D
authors.lastname: Sussman
authors.forename: Betty
authors.initials: B
authors.lastname: Shen
authors.forename: Robert
authors.initials: R
authors.lastname: Maunus
authors.forename: Jay
authors.initials: J
authors.lastname: Nix
authors.forename: James
authors.initials: J
authors.lastname: Samuelson
authors.forename: Shuang-Yong
authors.initials: SY
authors.lastname: Xu
authors.forename: Barry L
authors.initials: BL
authors.lastname: Stoddard
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D004247:DNA; D007501:Iron; D015252:Deoxyribonucleases, Type II Site-Specific; C038565:GCGGCCGC-specific type II deoxyribonucleases