PLoS ONE (Jan 2011)

A histone-like protein of mycobacteria possesses ferritin superfamily protein-like activity and protects against DNA damage by Fenton reaction.

  • Masaki Takatsuka,
  • Mayuko Osada-Oka,
  • Eisuke F Satoh,
  • Kengo Kitadokoro,
  • Yukiko Nishiuchi,
  • Mamiko Niki,
  • Masayasu Inoue,
  • Kazuhiro Iwai,
  • Tetsuo Arakawa,
  • Yoshihiro Shimoji,
  • Hisashi Ogura,
  • Kazuo Kobayashi,
  • Anura Rambukkana,
  • Sohkichi Matsumoto

DOI
https://doi.org/10.1371/journal.pone.0020985
Journal volume & issue
Vol. 6, no. 6
p. e20985

Abstract

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Iron is an essential metal for living organisms but its level must be strictly controlled in cells, because ferrous ion induces toxicity by generating highly active reactive oxygen, hydroxyl radicals, through the Fenton reaction. In addition, ferric ion shows low solubility under physiological conditions. To overcome these obstacles living organisms possess Ferritin superfamily proteins that are distributed in all three domains of life: bacteria, archaea, and eukaryotes. These proteins minimize hydroxyl radical formation by ferroxidase activity that converts Fe(2+) into Fe(3+) and sequesters iron by storing it as a mineral inside a protein cage. In this study, we discovered that mycobacterial DNA-binding protein 1 (MDP1), a histone-like protein, has similar activity to ferritin superfamily proteins. MDP1 prevented the Fenton reaction and protects DNA by the ferroxidase activity. The K(m) values of the ferroxidase activity by MDP1 of Mycobacterium bovis bacillus Calmette-Guérin (BCG-3007c), Mycobacterium tuberculosis (Rv2986c), and Mycobacterium leprae (ML1683; ML-LBP) were 0.292, 0.252, and 0.129 mM, respectively. Furthermore, one MDP1 molecule directly captured 81.4±19.1 iron atoms, suggesting the role of this protein in iron storage. This study describes for the first time a ferroxidase-iron storage protein outside of the ferritin superfamily proteins and the protective role of this bacterial protein from DNA damage.