On 2015 Nov 03, Martine Crasnier-Mednansky commented:

Figure 7 is improperly done and rife with error. One of the characteristic of the PTS is that its substrates are transported and phosphorylated concomitantly. Therefore glucose phosphorylation does not occur inside the cell as depicted in the figure. Representation of the phosphorylation state of the PTS proteins is misleading (a pale P for Enzyme IIA^Glc does not lead to a dark P for Enzyme IICB^Glc).

The figure legend wrongly indicates excess glucose increases the level of 2-oxoglutarate thereby inhibiting the phosphorylation cascade. In fact 2-oxoglutarate, which accumulates in nitrogen limitation, inhibits the PTS phosphorylation cascade Doucette CD, 2011. On the other hand, an increase in nitrogen availability (figure 7C) causes an increase in glucose uptake, which cannot possibly activate adenylate cyclase to allow for transport of alternative carbon sources (in these conditions, glucose transport also prevents utilization of alternative carbon sources due to inducer exclusion). Thus, in the presence of glucose, a decrease in 2-oxoglutarate upon sudden nitrogen availability is unlikely to 'partially activate adenylate cyclase' and 'activate carbon catabolite pathways', as stated in the figure legend.

A direct inhibition of adenylate cyclase by 2-oxoglutarate, as depicted in Figure 7B, relies on questionable studies (see PubMed Commons comment attached to You C, 2013), and is not supported by data from Yang JK, 1983 (Table VII, caption a) indicating 10 mM 2-oxoglutarate (α-ketoglutarate) did not inhibit adenylate cyclase activity.

On 2015 Nov 03, Martine Crasnier-Mednansky commented:

Figure 7 is improperly done and rife with error. One of the characteristic of the PTS is that its substrates are transported and phosphorylated concomitantly. Therefore glucose phosphorylation does not occur inside the cell as depicted in the figure. Representation of the phosphorylation state of the PTS proteins is misleading (a pale P for Enzyme IIA^Glc does not lead to a dark P for Enzyme IICB^Glc).

The figure legend wrongly indicates excess glucose increases the level of 2-oxoglutarate thereby inhibiting the phosphorylation cascade. In fact 2-oxoglutarate, which accumulates in nitrogen limitation, inhibits the PTS phosphorylation cascade Doucette CD, 2011. On the other hand, an increase in nitrogen availability (figure 7C) causes an increase in glucose uptake, which cannot possibly activate adenylate cyclase to allow for transport of alternative carbon sources (in these conditions, glucose transport also prevents utilization of alternative carbon sources due to inducer exclusion). Thus, in the presence of glucose, a decrease in 2-oxoglutarate upon sudden nitrogen availability is unlikely to 'partially activate adenylate cyclase' and 'activate carbon catabolite pathways', as stated in the figure legend.

A direct inhibition of adenylate cyclase by 2-oxoglutarate, as depicted in Figure 7B, relies on questionable studies (see PubMed Commons comment attached to You C, 2013), and is not supported by data from Yang JK, 1983 (Table VII, caption a) indicating 10 mM 2-oxoglutarate (α-ketoglutarate) did not inhibit adenylate cyclase activity.