Vitreoscilla hemoglobin promoter is not responsive to nitrosative and oxidative stress in Escherichia coli

Alexander D. Frey*, Taija Koskenkorva, Pauli T. Kallio

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)


The Vitreoscilla hemoglobin gene (vhb) is expressed under oxygen-limited conditions via an FNR-dependent mechanism. Furthermore, cAMP-CRP has been implicated in its regulation. Recently, VHb protein has been reported to protect a heterologous host from nitrosative stress. In this study we analyzed the regulation of the Vitreoscilla hemoglobin promoter (Pvhb) in Escherichia coli under nitrosative and oxidative stress conditions. Our results show unambiguously that expression of neither VHb nor chloramphenicol acetyltransferase under the control of Pvhb is induced under the experimental conditions used. Thus, a clear discrepancy between in vivo function, i.e. protection against nitrosative stress, and regulation of gene expression is obvious. The regulation of Pvhb reported here is in clear contrast to the expression pattern of flavohemoglobins from various microorganisms, which are generally induced by nitrosative stress. However, the length of Pvhb is only 146 bp and therefore, we cannot rule out that additional regulatory sequences may be located in the upstream region of Pvhb.

Original languageEnglish
Pages (from-to)127-132
Number of pages6
JournalFEMS Microbiology Letters
Issue number1
Publication statusPublished - 1 Jul 2003
MoE publication typeA1 Journal article-refereed


  • Gene regulation
  • Nitrosative stress
  • Oxidative stress
  • Vitreoscilla hemoglobin


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