PARENT SESSION

Symposium S2B Light, redox and metabolic regulation: Light reactions
Monday August 30th, 2004 2:40 PM-4:40 PM Room 210A
Chair: Frances-Andre Wollman
Co-Chair: Kris Niyogi

Characterization and function of the six bacteriophytochromes of Rhodopseudomonas palustris. Eric Giraud¹, Sébastien Zappa², Laurie Vuillet¹, Joel Fardoux¹, Laure Hannibal¹, Catherine Berthomieu², David Pignol ², Andre Vermeglio^*,2, ¹ Laboratoire des Symbioses Tropicales et Méditerranéennes, IRD, CIRAD, Montpellier, France² CEA Cadarache DEVM:LBC, Saint Paul lez Durance, france

ABSTRACT- The sequencing of the complete genome of Rhodopseudomonas palustris (Larimer et al., 2004, Nature Biotechnology22, 55 - 61) has revealed the presence of six different genes encoding for putative bacteriophytochromes. We have purified these six putative bacteriophytochromes after expression in E. coli together with the heme oxygenase necessary for the synthesis of their chromophore (Biliverdin). These six bacteriophytochromes have been characterized in terms of absorption and luorescence properties, light induced absorbance changes in the UV-Vis and mid IR region (using FTIR spectroscopy), life time and phosphorylation state of the Pr and Pfr forms. The amino acids involved in the binding of the chromophore biliverdine have been determined by site directed mutagenesis. Based on the location of each of these genes in the genome and on the phenotypes of some deletion mutants, we will discuss their putative function in the regulation of the essential components of the photosynthetic unit.

KEY WORDS: bacteriophytochrome, reaction center, antennae, Rhodopseudomonas palustris, light regulation