Open AccessTwo pathways of electron transport to nitrogenase in Rhodospirillum rubrum : the major pathway is dependent on the fix gene products
Author(s) -
Edgren Tomas,
Nordlund Stefan
Publication year - 2006
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2006.00297.x
Subject(s) - rhodospirillum rubrum , nitrogenase , ferredoxin , diazotroph , oxidoreductase , mutant , electron transport chain , biology , rhodospirillaceae , photosynthesis , gene , electron transfer , biochemistry , bacteria , chemistry , biophysics , enzyme , genetics , nitrogen fixation , photochemistry
In the photosynthetic bacterium Rhodospirillum rubrum , as in many other diazotrophs, electron transport to nitrogenase has not been characterized in great detail. In this study, we show that there are two pathways operating in R. rubrum . The products of the fix genes constitute the major pathway operating under heterotrophic conditions, whereas a pyruvate:ferredoxin oxidoreductase, encoded by the nifJ gene, may play a central role under anaerobic conditions in the dark. In both systems, ferredoxin N is the main direct electron donor to dinitrogenase reductase. Furthermore, we suggest from studying mutants lacking components in one or both systems under different conditions, that the Fix system operates most efficiently under conditions when a proton motive force is generated. A model for our current view of the electron transfer pathways in R. rubrum is presented.