Electron transport to nitrogenase in Rhodospirillum rubrum: the role of NAD(P)H as electron donor and the effect of fluoroacetate on nitrogenase activity
Erica Brostedt
Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
Search for more papers by this authorAnders Lindblad
Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
Search for more papers by this authorJanet Jansson
Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
Search for more papers by this authorCorresponding Author
Stefan Nordlund
Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
Corresponding author. Tel.: +46 (8) 16 29 32; fax: +46 (8) 15 77 94 or 15 36 79; e-mail: [email protected]Search for more papers by this authorErica Brostedt
Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
Search for more papers by this authorAnders Lindblad
Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
Search for more papers by this authorJanet Jansson
Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
Search for more papers by this authorCorresponding Author
Stefan Nordlund
Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
Corresponding author. Tel.: +46 (8) 16 29 32; fax: +46 (8) 15 77 94 or 15 36 79; e-mail: [email protected]Search for more papers by this authorAbstract
The role of the reactions of the TCA cycle in the generation of reductant for nitrogenase in Rhodospirillum rubrum has been investigated. Addition of fluoroacetate inhibited nitrogenase activity almost completely when pyruvate or endogenous sources were used as electron donors, whereas the inhibition was incomplete when malate, succinate or fumarate were used. Addition of NAD(P)H to cells supported nitrogenase activity, both with and without prior addition of fluoroacetate. We suggest that the role of the TCA cycle in nitrogen fixation in R. rubrum is to generate reduced pyridine nucleotides which are oxidized by the components of the electron transport pathway to nitrogenase.
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