Format

Send to

Choose Destination
Nucleic Acids Res. 2016 Nov 16;44(20):9965-9976. Epub 2016 Sep 15.

Molecular basis of cobalamin-dependent RNA modification.

Author information

1
Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
2
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
3
Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA.
4
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
5
Department of Chemistry, Boston University, Boston, MA 02215, USA.
6
Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA cdrennan@mit.edu.

Abstract

Queuosine (Q) was discovered in the wobble position of a transfer RNA (tRNA) 47 years ago, yet the final biosynthetic enzyme responsible for Q-maturation, epoxyqueuosine (oQ) reductase (QueG), was only recently identified. QueG is a cobalamin (Cbl)-dependent, [4Fe-4S] cluster-containing protein that produces the hypermodified nucleoside Q in situ on four tRNAs. To understand how QueG is able to perform epoxide reduction, an unprecedented reaction for a Cbl-dependent enzyme, we have determined a series of high resolution structures of QueG from Bacillus subtilis Our structure of QueG bound to a tRNATyr anticodon stem loop shows how this enzyme uses a HEAT-like domain to recognize the appropriate anticodons and position the hypermodified nucleoside into the enzyme active site. We find Q bound directly above the Cbl, consistent with a reaction mechanism that involves the formation of a covalent Cbl-tRNA intermediate. Using protein film electrochemistry, we show that two [4Fe-4S] clusters adjacent to the Cbl have redox potentials in the range expected for Cbl reduction, suggesting how Cbl can be activated for nucleophilic attack on oQ. Together, these structural and electrochemical data inform our understanding of Cbl dependent nucleic acid modification.

PMID:
27638883
PMCID:
PMC5175355
DOI:
10.1093/nar/gkw806
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Silverchair Information Systems Icon for PubMed Central
Loading ...
Support Center