Orf4 of the Bacillus cereus sigB gene cluster encodes a general stress-inducible dps-like bacterioferritin

Shin Wei Wang, Chien Yen Chen, Ta-Chien Tseng, Shih Hsiung Liang, Ssu Ching Chen, Chienyan Hsieh, Yen Hsu Chen, Chien Cheng Chen

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The function of orf4 in the sigB cluster in Bacillus cereus ATCC 14579 remains to be explored. Amino-acid sequence analysis has revealed that Orf4 is homologous with bacterioferritins and Dps. In this study, we generated an orf4-null mutant and produced recombinant protein rOrf4 to establish the role of orf4. In vitro, the purified rOrf4 was found to exist in two distinct forms, a dimeric form and a polymer form, through size exclusion analysis. The latter form exhibited a unique filament structure, in contrast to the typical spherical tetracosamer structure of bacterioferritins; the former can be induced to form rOrf4 polymers immediately after the addition of FeCl2. Catalysis of the oxidation of ferrous irons by ferroxidase activity was detected with rOrf4, and the mineralized irons were subsequently sequestered only in the rOrf4 polymer. Moreover, rOrf4 exerted DNA-protective activity against oxidative damage via DNA binding in a nonspecific manner, as is seen with Dps. In vivo, deletion of orf4 had no effect on activation of the alternative sigma factor σB, and therefore, orf4 is not associated with σB regulation; however, orf4 can be significantly upregulated upon environmental stress but not H2O2 treatment. B. cereus strains with constitutive Orf4 expression exhibited a viability higher than that of the orf4-null mutant, under specific oxidative stress or heat shock. Taken together, these results suggest that Orf4 functions as a Dps-like bacterioferritin in response to environmental stress and can provide cell protection from oxidative damage through iron sequestration and DNA binding.

Original languageEnglish
Pages (from-to)4522-4533
Number of pages12
JournalJournal of Bacteriology
Volume191
Issue number14
DOIs
Publication statusPublished - 2009 Jul 1

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Bacillus cereus
Multigene Family
Polymers
Sigma Factor
Ceruloplasmin
Cytoprotection
DNA
Protein Sequence Analysis
Catalysis
Recombinant Proteins
DNA Damage
Shock
Oxidative Stress
Iron
Hot Temperature
bacterioferritin

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Molecular Biology

Cite this

Wang, Shin Wei ; Chen, Chien Yen ; Tseng, Ta-Chien ; Liang, Shih Hsiung ; Chen, Ssu Ching ; Hsieh, Chienyan ; Chen, Yen Hsu ; Chen, Chien Cheng. / Orf4 of the Bacillus cereus sigB gene cluster encodes a general stress-inducible dps-like bacterioferritin. In: Journal of Bacteriology. 2009 ; Vol. 191, No. 14. pp. 4522-4533.
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Orf4 of the Bacillus cereus sigB gene cluster encodes a general stress-inducible dps-like bacterioferritin. / Wang, Shin Wei; Chen, Chien Yen; Tseng, Ta-Chien; Liang, Shih Hsiung; Chen, Ssu Ching; Hsieh, Chienyan; Chen, Yen Hsu; Chen, Chien Cheng.

In: Journal of Bacteriology, Vol. 191, No. 14, 01.07.2009, p. 4522-4533.

Research output: Contribution to journalArticle

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