Extended Data Fig. 7: Ammonium repression of the transferred nif clusters in E. coli MG1655 and P. protegens Pf-5.
From: Control of nitrogen fixation in bacteria that associate with cereals
Nitrogenase sensitivity to ammonium was measured by acetylene reduction assay in the absence (-) or presence (+) of 17.1 mM ammonium acetate. The sensitivity of the native and inducible nif clusters in E. coli MG1655 (a) and P. protegens Pf- 5 (b). Note that the data are from Fig. 4 and Supplementary Figure 8. (c) The specific nitrogenase activities of the native A. vinelandii nif cluster are compared to the inducible A. vinelandii cluster in the presence (+) and absence (-) of 17.1 mM ammonium acetate in P. protegens Pf-5. The nif clusters from the inducible version were induced by 50 μM and 0.5 mM IPTG in E. coli MG1655 and P. protegens Pf-5, respectively. Asterisks indicate ethylene production below the detection limit. Error bars represent standard deviation from three independent experiments on different days.
