Format

Send to

Choose Destination
See comment in PubMed Commons below
Proc Natl Acad Sci U S A. 2011 Dec 27;108(52):21046-51. doi: 10.1073/pnas.1112715108. Epub 2011 Dec 12.

Structural interconversions modulate activity of Escherichia coli ribonucleotide reductase.

Author information

1
Department of Chemistry, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Abstract

Essential for DNA biosynthesis and repair, ribonucleotide reductases (RNRs) convert ribonucleotides to deoxyribonucleotides via radical-based chemistry. Although long known that allosteric regulation of RNR activity is vital for cell health, the molecular basis of this regulation has been enigmatic, largely due to a lack of structural information about how the catalytic subunit (α(2)) and the radical-generation subunit (β(2)) interact. Here we present the first structure of a complex between α(2) and β(2) subunits for the prototypic RNR from Escherichia coli. Using four techniques (small-angle X-ray scattering, X-ray crystallography, electron microscopy, and analytical ultracentrifugation), we describe an unprecedented α(4)β(4) ring-like structure in the presence of the negative activity effector dATP and provide structural support for an active α(2)β(2) configuration. We demonstrate that, under physiological conditions, E. coli RNR exists as a mixture of transient α(2)β(2) and α(4)β(4) species whose distributions are modulated by allosteric effectors. We further show that this interconversion between α(2)β(2) and α(4)β(4) entails dramatic subunit rearrangements, providing a stunning molecular explanation for the allosteric regulation of RNR activity in E. coli.

PMID:
22160671
PMCID:
PMC3248520
DOI:
10.1073/pnas.1112715108
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center