429d

[[Image:429d.gif|left|200px]]<br /><applet load="429d" size="350" color="white" frame="true" align="right" spinBox="true"

caption="429d, resolution 2.70&Aring;" />

'''CRYSTAL STRUCTURE OF A LEADZYME; METAL BINDING AND IMPLICATIONS FOR CATALYSIS'''<br />

==Overview==

The leadzyme is a small RNA motif that catalyzes a site-specific, Pb2+-dependent cleavage reaction. As such, it is an example of a metal-dependent RNA enzyme. Here we describe the X-ray crystallographic structure of the leadzyme, which reveals two independent molecules per asymmetric unit. Both molecules feature an internal loop in which a bulged purine base stack twists away from the helical stem. This kinks the backbone, rendering the phosphodiester bond susceptible to cleavage. The independent molecules have different conformations: one leadzyme copy coordinates Mg2+, whereas the other binds only Ba2+ or Pb2+. In the active site of the latter molecule, a single Ba2+ ion coordinates the 2'-OH nucleophile, and appears to mimic the binding of catalytic lead. These observations allow a bond cleavage reaction to be modeled, which reveals the minimal structural features necessary for catalysis by this small ribozyme.

==About this Structure==

429D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ] with <scene name='pdbligand=MG:'>MG</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=429D OCA].

 

Crystal structure of a lead-dependent ribozyme revealing metal binding sites relevant to catalysis., Wedekind JE, McKay DB, Nat Struct Biol. 1999 Mar;6(3):261-8. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10074945 10074945]

[[Category: Protein complex]]

[[Category: McKay, D. B.]]

[[Category: Wedekind, J. E.]]