4al6: Difference between revisions

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-[[Image:4al6.png|left|200px]]
+==Crystal structure of the S148ACsy4-crRNA complex==
+<StructureSection load='4al6' size='340' side='right' caption='[[4al6]], [[Resolution|resolution]] 2.63&Aring;' scene=''>
+== Structural highlights ==
+<table><tr><td colspan='2'>[[4al6]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa Pseudomonas aeruginosa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4AL6 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4AL6 FirstGlance]. <br>
+</td></tr><tr><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4al5|4al5]], [[4al7|4al7]]</td></tr>
+<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4al6 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4al6 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4al6 RCSB], [http://www.ebi.ac.uk/pdbsum/4al6 PDBsum]</span></td></tr>
+<table>
+<div style="background-color:#fffaf0;">
+== Publication Abstract from PubMed ==
+CRISPR-Cas adaptive immune systems protect prokaryotes against foreign genetic elements. crRNAs derived from CRISPR loci base pair with complementary nucleic acids, leading to their destruction. In Pseudomonas aeruginosa, crRNA biogenesis requires the endoribonuclease Csy4, which binds and cleaves the repetitive sequence of the CRISPR transcript. Biochemical assays and three co-crystal structures of wild-type and mutant Csy4/RNA complexes reveal a substrate positioning and cleavage mechanism in which a histidine deprotonates the ribosyl 2'-hydroxyl pinned in place by a serine, leading to nucleophilic attack on the scissile phosphate. The active site catalytic dyad lacks a general acid to protonate the leaving group and positively charged residues to stabilize the transition state, explaining why the observed catalytic rate constant is approximately 10(4)-fold slower than that of RNase A. We show that this RNA cleavage step is essential for assembly of the Csy protein-crRNA complex that facilitates target recognition. Considering that Csy4 recognizes a single cellular substrate and sequesters the cleavage product, evolutionary pressure has likely selected for substrate specificity and high-affinity crRNA interactions at the expense of rapid cleavage kinetics.
-{{STRUCTURE_4al6|  PDB=4al6  |  SCENE=  }}
+Csy4 relies on an unusual catalytic dyad to position and cleave CRISPR RNA.,Haurwitz RE, Sternberg SH, Doudna JA EMBO J. 2012 Apr 20. doi: 10.1038/emboj.2012.107. PMID:22522703<ref>PMID:22522703</ref>
-===Crystal structure of the S148ACsy4-crRNA complex===
+From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
+</div>
-{{ABSTRACT_PUBMED_22522703}}
+== References ==
+<references/>
-==About this Structure==
+__TOC__
-[[4al6]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa Pseudomonas aeruginosa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4AL6 OCA].
+</StructureSection>
-==Reference==
-<ref group="xtra">PMID:022522703</ref><references group="xtra"/>
 [[Category: Pseudomonas aeruginosa]]
 [[Category: Doudna, J A.]]