Structural highlights
Publication Abstract from PubMed
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.
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:10074945[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Wedekind JE, McKay DB. Crystal structure of a lead-dependent ribozyme revealing metal binding sites relevant to catalysis. Nat Struct Biol. 1999 Mar;6(3):261-8. PMID:10074945 doi:10.1038/6700
