View source for 2qoj


==Coevolution of a homing endonuclease and its host target sequence==
<StructureSection load='2qoj' size='340' side='right'caption='[[2qoj]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2qoj]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Aspergillus_nidulans_FGSC_A4 Aspergillus nidulans FGSC A4]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2QOJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2QOJ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.4&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2qoj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2qoj OCA], [https://pdbe.org/2qoj PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2qoj RCSB], [https://www.ebi.ac.uk/pdbsum/2qoj PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2qoj ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/ANI1_EMEND ANI1_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.<ref>PMID:9256423</ref> <ref>PMID:10512698</ref> <ref>PMID:12758073</ref> 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/qo/2qoj_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2qoj ConSurf].
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== Publication Abstract from PubMed ==
We have determined the specificity profile of the homing endonuclease I-AniI and compared it to the conservation of its host gene. Homing endonucleases are encoded within intervening sequences such as group I introns. They initiate the transfer of such elements by cleaving cognate alleles lacking the intron, leading to their transfer via homologous recombination. Each structural homing endonuclease family has arrived at an appropriate balance of specificity and fidelity that avoids toxicity while maximizing target recognition and invasiveness. I-AniI recognizes a strongly conserved target sequence in a host gene encoding apocytochrome B and has fine-tuned its specificity to correlate with wobble versus nonwobble positions across that sequence and to the amount of degeneracy inherent in individual codons. The physiological target site in the host gene is not the optimal substrate for recognition and cleavage: at least one target variant identified during a screen is bound more tightly and cleaved more rapidly. This is a result of the periodic cycle of intron homing, which at any time can present nonoptimal combinations of endonuclease specificity and insertion site sequences in a biological host.

Coevolution of a homing endonuclease and its host target sequence.,Scalley-Kim M, McConnell-Smith A, Stoddard BL J Mol Biol. 2007 Oct 5;372(5):1305-19. Epub 2007 Aug 2. PMID:17720189<ref>PMID:17720189</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 2qoj" style="background-color:#fffaf0;"></div>

==See Also==
*[[Endonuclease 3D structures|Endonuclease 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Aspergillus nidulans FGSC A4]]
[[Category: Large Structures]]
[[Category: McConnell Smith A]]
[[Category: Scalley-Kim M]]
[[Category: Stoddard BL]]