Photosynthesis Research

, Volume 57, Issue 2, pp 117-128

First online:

Photoinduced electron transfer and cytochrome content in obligate aerobic phototrophic bacteria from genera Erythromicrobium, Sandaracinobacter, Erythromonas, Roseococcus and Erythrobacter

  • Vladimir YurkovAffiliated withLaboratoire de Bioénergétique Cellulaire, CEA/Cadarache, DEVM
  • , Barbara SchoeppAffiliated withLaboratoire d'Ingénierie des Protéines, Centre de Génétique Moléculaire, CNRS
  • , André VerméglioAffiliated withLaboratoire de Bioénergétique Cellulaire, CEA/Cadarache, DEVM

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The photosynthetic apparatus and the electron carriers of seven species of five different genera of obligate aerobic phototrophic bacteria have been characterized by biochemical and biophysical techniques. A tetrahemic reaction center (RC) bound cytochrome (cyt) was found in Erythromonas (Em.) ursincola, Sandaracinobacter (S.) sibiricus and Roseococcus (R.) thiosulfatophilus, but not in Erythromicrobium (E.) ezovicum, Erythromicrobium ramosum, Erythromicrobium hydrolyticum and Erythrobacter (Eb.) litoralis. In none of the studied species, photochemical activity was observed under anaerobic conditions. Under aerobic conditions, the photoinduced cyclic electron transfer involves a soluble c-type cyt for the seven species. The cyt content of soluble and membrane fractions is highly dependent upon the species. The Erythromicrobium species (E. ezovicum, E. ramosum and E. hydrolyticum) contains a major soluble cyt while the other species possess several soluble cyts, up to four in the case of Eb. litoralis. These cyts have been characterized in terms of midpoint potential and apparent molecular mass. The presence of cyt bc1 complexes has been clearly detected in Eb. litoralis, E. hydrolyticum, E. ezovicum and E. ramosum. These last three species also contain a high midpoint potential (350 mV) membrane-bound cyt c of unknown function.

aerobic phototrophic bacteria cytochrome electron transfer