Bacterial hemoglobins and flavohemoglobins: Versatile proteins and their impact on microbiology and biotechnology

Alexander D. Frey, Pauli T. Kallio*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

171 Citations (Scopus)


In response to oxygen limitation or oxidative and nitrosative stress, bacteria express three kinds of hemoglobin proteins: truncated hemoglobins (tr Hbs), hemoglobins (Hbs) and flavohemoglobins (flavo Hbs). The two latter groups share a high sequence homology and structural similarity in their globin domain. Flavohemoglobin proteins contain an additional reductase domain at their C-terminus and their expression is induced in the presence of reactive nitrogen and oxygen species. Flavohemoglobins detoxify NO in an aerobic process, termed nitric oxide dioxygenase reaction, which protects the host from various noxious nitrogen compounds. Only a small number of bacteria express hemoglobin proteins and the best studied of these is from Vitreoscilla sp. Vitreoscilla hemoglobin (VHb) has been expressed in various heterologous hosts under oxygen-limited conditions and has been shown to improve growth and productivity, rendering the protein interesting for biotechnology industry. The close interaction of VHb with the terminal oxidases has been shown and this interplay has been proposed to enhance respiratory activity and energy production by delivering oxygen, the ultimate result being an improvement in growth properties.

Original languageEnglish
Pages (from-to)525-545
Number of pages21
Issue number4
Publication statusPublished - 1 Oct 2003
MoE publication typeA1 Journal article-refereed


  • Biotechnological application
  • Microaerobic growth
  • Nitric oxide detoxification
  • Nitrosative stress
  • Pathogenic bacteria
  • Protein engineering


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