title: Identification of novel genes putatively involved in the photosystem synthesis of Bradyrhizobium sp. ORS 278.
abstract: In aerobic anoxygenic phototrophs, oxygen is required for both the formation of the photosynthetic apparatus and an efficient cyclic electron transfer. Mutants of Bradyrhizobium sp. ORS278 affected in photosystem synthesis were selected by a bacteriochlorophyll fluorescence-based screening. Out of the 9,600 mutants of a random Tn5 insertion library, 50 clones, corresponding to insertions in 28 different genes, present a difference in fluorescence intensity compared to the WT. Besides enzymes and regulators known to be involved in photosystem synthesis, 14 novel components of the photosynthesis control are identified. Among them, two genes, hsIU and hsIV, encode components of a protein degradation complex, probably linked to the renewal of photosystem, an important issue in Bradyrhizobia which have to deal with harmful reactive oxygen species. The presence of homologs in non-photosynthetic bacteria for most of the regulatory genes identified during study suggests that they could be global regulators, as the RegA-RegB system.
authors.affiliation: Laboratoire des Symbioses Tropicales et Méditerranéennes, IRD, CIRAD, AGRO-M, INRA, UM2. TA A-82/J, Campus de Baillarguet, 34398, Montpellier Cedex 5, France.
authors.forename: Marianne
authors.initials: M
authors.lastname: Jaubert
authors.forename: Laure
authors.initials: L
authors.lastname: Hannibal
authors.forename: Joël
authors.initials: J
authors.lastname: Fardoux
authors.forename: Eric
authors.initials: E
authors.lastname: Giraud
authors.forename: André
authors.initials: A
authors.lastname: Verméglio
mesh_terms: D001429:Bacteriochlorophylls / Q000378:metabolism; D020369:Bradyrhizobium / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects; D002999:Clone Cells; D005798:Genes, Bacterial; D008027:Light; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D010788:Photosynthesis / Q000235:genetics / Q000528:radiation effects; D045322:Photosynthetic Reaction Center Complex Proteins / Q000096:biosynthesis*; D013050:Spectrometry, Fluorescence
chemical_list: D001429:Bacteriochlorophylls; D045322:Photosynthetic Reaction Center Complex Proteins