Two Active Site Divalent Ions in the Crystal Structure of the Hammerhead Ribozyme Bound to a Transition State Analogue.
Biochemistry
; 55(4): 633-6, 2016 Feb 02.
Article
in En
| MEDLINE
| ID: mdl-26551631
ABSTRACT
The crystal structure of the hammerhead ribozyme bound to the pentavalent transition state analogue vanadate reveals significant rearrangements relative to the previously determined structures. The active site contracts, bringing G10.1 closer to the cleavage site and repositioning a divalent metal ion such that it could, ultimately, interact directly with the scissile phosphate. This ion could also position a water molecule to serve as a general acid in the cleavage reaction. A second divalent ion is observed coordinated to O6 of G12. This metal ion is well-placed to help tune the pKA of G12. On the basis of this crystal structure as well as a wealth of biochemical studies, we propose a mechanism in which G12 serves as the general base and a magnesium-bound water serves as a general acid.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
RNA, Catalytic
/
Magnesium
/
Nucleic Acid Conformation
Language:
En
Journal:
Biochemistry
Year:
2016
Document type:
Article
Affiliation country:
United States