A polymorphism in the oxygen-responsive repressor PpsR2 confers a growth advantage to Rhodopseudomonas palustris under low light

Kathryn R. Fixen, Caroline S. Harwood

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The purple nonsulfur bacterium Rhodopseudomonas palustris grows aerobically using oxidative phosphorylation or anaerobically using photophosphorylation. The oxygen-responsive transcription regulator, PpsR2, regulates the transition to a phototrophic lifestyle by repressing transcription of photosynthesis genes during aerobic growth. Whereas most R. palustris strains have an arginine (Arg) at position 439 in the helix-turn-helix DNA-binding domain of this protein, some strains, including the well-studied strain CGA009, have a cysteine (Cys) at this position. Using allelic exchange, we found that the Cys439 in PpsR2 resulted in increased pigmentation and photosynthetic gene expression under both aerobic and anaerobic conditions. The Cys439 substitution also conferred a growth advantage to R. palustris at low light intensities. This indicates that variation in the PpsR2 protein results in R. palustris strains that have two different thresholds for derepressing photosynthesis genes in response to oxygen and light.

Original languageEnglish (US)
Pages (from-to)199-204
Number of pages6
JournalPhotosynthesis Research
Volume129
Issue number2
DOIs
StatePublished - Aug 1 2016

Bibliographical note

Funding Information:
We thank Dr. J. Thomas Beatty (University of British Columbia) for providing strain CGA009 bphP1. The Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, U.S. Department of Energy (DOE) funded this work, through Grant DE-FG02-05ER15707. +

Publisher Copyright:
© 2016, Springer Science+Business Media Dordrecht.

Keywords

  • Bacteriophytochrome
  • Low light
  • Photosynthesis
  • PpsR2
  • Rhodopseudomonas

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