Characterization and radio-resistant function of manganese superoxide dismutase of rubrobacter radiotolerans

Hiroaki Terato, Katsuyuki Suzuki, Nobuhiro Nishioka, Atsushi Okamoto, Yuka Shimazaki-Tokuyama, Yuko Inoue, Takeshi Saito

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Rubrobacter radiotolerans is the most radio-resistant eubacterium without spore-formation in the life cycle, and its D37 is 16,000 Gy against gamma-rays. To understand the molecular mechanism of the high radio-resistance, we purified and characterized superoxide dismutase (SOD) of this organism as enzymatic radical scavenger, and then analyzed its genetic information. The purified SOD protein formed homo-tetramerization of 24,000 Da-monomer, while maintaining its enzymatic activity against potassium cyanide and hydrogen peroxide. We obtained a partial amino acid sequence of the protein and cloned the gene from it. Sequence analysis of the cloned gene indicated that the protein showed a similarity to other bacterial manganese SODs (Mn-SODs). Sequencing for adjacent regions of the gene showed that the gene had promoter elements with an open reading frame for putative PAS/PAC sensor protein at the 5'-adjacent region. Introduction of the gene into Escherichia coli cells lacking intrinsic SOD genes restored the cellular enzymatic activity and resistance to methyl viologen, indicating the gene at work. A mutant cell harboring this gene also became resistant against gamma-rays. The present results suggest that the protein in question is the Mn-SOD of R. radiotolerans, a good candidate as a radio-protection factor for this bacterial radio-resistance.

Original languageEnglish
Pages (from-to)735-742
Number of pages8
JournalJournal of radiation research
Issue number6
Publication statusPublished - Nov 2011
Externally publishedYes


  • Radical scavenger
  • Radio-resistance
  • Rubrobacter radiotolerans
  • Superoxide dismutase

ASJC Scopus subject areas

  • Radiation
  • Radiology Nuclear Medicine and imaging
  • Health, Toxicology and Mutagenesis


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