A ribonucleotide reductase from Clostridium botulinum reveals distinct evolutionary pathways to regulation via the overall activity site

Research output: Contribution to journalArticle

Abstract

Ribonucleotide reductase (RNR) is a central enzyme for DNA building block synthesis. Most aerobic organisms, including nearly all eukaryotes, have class I RNRs consisting of R1 and R2 subunits. The catalytic R1 subunit contains an overall activity site that can allosterically turn the enzyme on or off by the binding of ATP or dATP, respectively. The mechanism behind the ability to turn the enzyme off via the R1 subunit involves the formation of different types of R1 oligomers in most studied species and R1-R2 octamers in Escherichia coli. To better understand the distribution of different oligomerization mechanisms, we characterized the enzyme from Clostridium botulinum, which belongs to a subclass of class I RNRs not studied before. The recombinantly expressed enzyme was analyzed by size exclusion chromatography, gas-phase electrophoretic mobility macromolecular analysis, electron microscopy, x-ray crystallography, and enzyme assays. Interestingly, it shares the ability of the E. coli RNR to form inhibited R1-R2 octamers in the presence of dATP but, unlike the E. coli enzyme, cannot be turned off by combinations of ATP and dGTP/dTTP. A phylogenetic analysis of class I RNRs suggests that activity regulation is not ancestral, but was gained after the first subclasses diverged and that RNR subclasses with inhibition mechanisms involving R1 oligomerization belong to a clade separated from the two subclasses forming R1-R2 octamers. These results give further insight into activity regulation in class I RNRs as an evolutionarily dynamic process.

Details

Authors
  • Markel Martínez-Carranza
  • Venkateswara Rao Jonna
  • Daniel Lundin
  • Margareta Sahlin
  • Lars-Anders Carlson
  • Newal Jemal
  • Martin Högbom
  • Britt-Marie Sjöberg
  • Pål Stenmark
  • Anders Hofer
Organisations
External organisations
  • Umeå University
  • Stockholm University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Medicinal Chemistry
Original languageEnglish
JournalThe Journal of biological chemistry
Publication statusE-pub ahead of print - 2020 Sep 3
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

Published under license by The American Society for Biochemistry and Molecular Biology, Inc.