Color-sensitive motility and methanol release responses in Rhodobacter sphaeroides

R Kort, W. Crielaard, J L Spudich, K J Hellingwerf

Research output: Contribution to JournalArticleAcademicpeer-review


Blue-light-induced repellent and demethylation responses, characteristic of behavioral adaptation, were observed in Rhodobacter sphaeroides. They were analyzed by computer-assisted motion analysis and through the release of volatile tritiated compounds from [methyl-(3)H]methionine-labeled cells, respectively. Increases in the stop frequency and the rate of methanol release were induced by exposure of cells to repellent light signals, such as an increase in blue- and a decrease in infrared-light intensity. At a lambda of >500 nm the amplitude of the methanol release response followed the absorbance spectrum of the photosynthetic pigments, suggesting that they function as photosensors for this response. In contrast to the previously reported motility response to a decrease in infrared light, the blue-light response reported here does not depend on the number of photosynthetic pigments per cell, suggesting that it is mediated by a separate sensor. Therefore, color discrimination in taxis responses in R. sphaeroides involves two photosensing systems: the photosynthetic pigments and an additional photosensor, responding to blue light. The signal generated by the former system could result in the migration of cells to a light climate beneficial for photosynthesis, while the blue-light system could allow cells to avoid too-high intensities of (harmful) blue light.

Original languageEnglish
Pages (from-to)3017-21
Number of pages5
JournalJournal of Bacteriology
Issue number11
Publication statusPublished - Jun 2000


  • Bacterial Proteins
  • Chemotaxis
  • Color
  • Image Processing, Computer-Assisted
  • Light
  • Membrane Proteins
  • Methanol
  • Methyl-Accepting Chemotaxis Proteins
  • Models, Biological
  • Photosynthesis
  • Rhodobacter sphaeroides
  • Signal Transduction
  • Journal Article
  • Research Support, Non-U.S. Gov't


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