Molecular and General Genetics MGG

, Volume 215, Issue 3, pp 507–516

The DNA sequence of the Rhodobacter capsulatus ntrA, ntrB and ntrC gene analogues required for nitrogen fixation

  • Robert Jones
  • Robert Haselkorn

DOI: 10.1007/BF00427050

Cite this article as:
Jones, R. & Haselkorn, R. Molec. Gen. Genet. (1989) 215: 507. doi:10.1007/BF00427050


We have determined the DNA sequence for the genes nifR1, nifR2 and nifR4 in the photosynthetic bacterium Rhodobacter capsulatus. These genes regulate transcription of the nifHDK operon and so limit the expression of nitrogen fixation activity to periods of low environmental concentrations of both oxygen and fixed nitrogen. The sequences of these three genes are similar to components of the ntr regulation system in Escherichia coli and Klebsiella pneumoniae. The two-component regulatory system of ntrB and ntrC in E. coli is represented by nifR2 and nifR1 in R. capsulatus and nifR4 in R. capsulatus is the equivalent of the E. coli ntr-related sigma factor ntrA.

Key words

Nitrogen fixation Regulation Rhodobacter capsulatus Gene sequences Transcription factors 

Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • Robert Jones
    • 1
  • Robert Haselkorn
    • 1
  1. 1.Department of Molecular Genetics and Cell BiologyUniversity of chicagoChicagoUSA

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