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1dc1
From Proteopedia
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[[Image:1dc1.gif|left|200px]] | [[Image:1dc1.gif|left|200px]] | ||
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'''RESTRICTION ENZYME BSOBI/DNA COMPLEX STRUCTURE: ENCIRCLEMENT OF THE DNA AND HISTIDINE-CATALYZED HYDROLYSIS WITHIN A CANONICAL RESTRICTION ENZYME FOLD''' | '''RESTRICTION ENZYME BSOBI/DNA COMPLEX STRUCTURE: ENCIRCLEMENT OF THE DNA AND HISTIDINE-CATALYZED HYDROLYSIS WITHIN A CANONICAL RESTRICTION ENZYME FOLD''' | ||
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[[Category: Woerd, M J.van der.]] | [[Category: Woerd, M J.van der.]] | ||
[[Category: Xu, S Y.]] | [[Category: Xu, S Y.]] | ||
| - | [[Category: | + | [[Category: Degenerate dna recognition]] |
| - | [[Category: | + | [[Category: Protein-dna complex]] |
| - | [[Category: | + | [[Category: Restriction endonuclease]] |
| - | [[Category: | + | [[Category: Thermophilic enzyme]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:40:35 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 10:40, 2 May 2008
RESTRICTION ENZYME BSOBI/DNA COMPLEX STRUCTURE: ENCIRCLEMENT OF THE DNA AND HISTIDINE-CATALYZED HYDROLYSIS WITHIN A CANONICAL RESTRICTION ENZYME FOLD
Overview
BACKGROUND: Restriction endonucleases form a diverse family of proteins with substantial variation in sequence, structure, and interaction with recognition site DNA. BsoBI is a thermophilic restriction endonuclease that exhibits both base-specific and degenerate recognition within the sequence CPyCGPuG. RESULTS: The structure of BsoBI complexed to cognate DNA has been determined to 1.7 A resolution, revealing several unprecedented features. Each BsoBI monomer is formed by inserting a helical domain into an expanded EcoRI-type catalytic domain. DNA is completely encircled by a BsoBI dimer. Recognition sequence DNA lies within a 20 A long tunnel of protein that excludes bulk solvent. Interactions with the specific bases are made in both grooves through direct and water-mediated hydrogen bonding. Interaction with the degenerate position is mediated by a purine-specific hydrogen bond to N7, ensuring specificity, and water-mediated H bonding to the purine N6/O6 and pyrimidine N4/O4, allowing degeneracy. In addition to the conserved active site residues of the DX(n)(E/D)ZK restriction enzyme motif, His253 is positioned to act as a general base. CONCLUSIONS: A catalytic mechanism employing His253 and two metal ions is proposed. If confirmed, this would be the first example of histidine-mediated catalysis in a restriction endonuclease. The structure also provides two novel examples of the role of water in protein-DNA interaction. Degenerate recognition may be mediated by employing water as a hydrogen bond donor or acceptor. The structure of DNA in the tunnel may also be influenced by the absence of bulk solvent.
About this Structure
1DC1 is a Single protein structure of sequence from Geobacillus stearothermophilus. Full crystallographic information is available from OCA.
Reference
Restriction enzyme BsoBI-DNA complex: a tunnel for recognition of degenerate DNA sequences and potential histidine catalysis., van der Woerd MJ, Pelletier JJ, Xu S, Friedman AM, Structure. 2001 Feb 7;9(2):133-44. PMID:11250198 Page seeded by OCA on Fri May 2 13:40:35 2008
