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. Author manuscript; available in PMC: 2015 Jan 21.
Published in final edited form as: J Mol Biol. 2009 Mar 13;388(2):262–270. doi: 10.1016/j.jmb.2009.03.015

Figure 3.

Figure 3

Activation of BpeGReg by O2 and feedback inhibition of the enzyme by c-di-GMP. Rates of conversion of 500 µM GTP to c-di-GMP were followed either by measuring c-di-GMP directly or by measuring formation of pGpG from a PDE-coupled reaction. (a) Activity of 5 µM oxy-BpeGReg without coupling to a PDE, or with coupling to a PDE. (b) Activity of 1 µM oxy-BpeGReg in a reaction started in the presence of 20 µM c-di-GMP, or coupled to a PDE. (c) Activity of 5 µM BpeGReg in air (Fe(II)O2), or under anaerobic conditions (Fe(II)). Note the 13-fold drop in the activity in the absence of O2, and note that in air the reaction is essentially complete within 30 min. (d) TLC showing representative time points from the reactions shown in panel (c); the first three lanes are shown as references, with the Rf values being: GTP (0.58), c-di-GMP (0.18), and pGpG (0.34). (e) Repeat of the reactions shown in (c) for analysis by HPLC. (f) HPLC traces of representative pGpG peaks from the reactions shown in panel (e); the peaks are from the 2.5, 5.0, 10, 15, and 20 min time points.