3eh8
Crystal structure of Y2 I-AniI variant (F13Y/S111Y)/DNA complex with calcium
Structural highlights
FunctionANI1_EMEND Mitochondrial DNA endonuclease and mRNA maturase involved in intron homing and required for splicing of the cytochrome b (cobA) gene intron, containing its own coding sequence. The protein stimulates the intrinsic ribozyme activity of the intron through binding to and stabilizing specific secondary and tertiary structure elements in the RNA. As an endonuclease it introduces a specific double-strand break at the junction of the two exons the cobA gene and thus mediates the insertion of an intron, containing its own coding sequence (group I intron), into an intronless gene. Recognizes with limited specificity and cleaves the sequence 5'-GAGGAGGTTTCTCTGTA-3'. The proteins RNA and DNA recognition and binding surfaces are independent.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe LAGLIDADG homing endonuclease (LHE) I-AniI has adopted an extremely efficient secondary RNA splicing activity that is beneficial to its host, balanced against inefficient DNA cleavage. A selection experiment identified point mutations in the enzyme that act synergistically to improve endonuclease activity. The amino-acid substitutions increase target affinity, alter the thermal cleavage profile and significantly increase targeted recombination in transfected cells. The RNA splicing activity is not affected by these mutations. The improvement in DNA cleavage activity is largely focused on one of the enzyme's two active sites, corresponding to a rearrangement of a lysine residue hypothesized to act as a general base. Most of the constructs isolated in the screen contain one or more mutations that revert an amino-acid identity to a residue found in one or more close homologues of I-AniI. This implies that mutations that have previously reduced the endonuclease activity of I-AniI are identified and reversed, sometimes in combination with additional 'artificial' mutations, to optimize its in vivo activity. Optimization of in vivo activity of a bifunctional homing endonuclease and maturase reverses evolutionary degradation.,Takeuchi R, Certo M, Caprara MG, Scharenberg AM, Stoddard BL Nucleic Acids Res. 2008 Dec 22. PMID:19103658[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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