Figure 4.

Regulation of salt-induced GG-synthesis via the key enzyme GgpS involves different regulatory layers in Synechocystis. (A,B) Kinetics of ggpS mRNA, GgpS protein, GG accumulation, and changes of salt ion concentrations after sudden salt shocks in Synechocystis [data have been obtained from Marin et al., 2002 (A) and Reed et al., 1985 (B)]. (C) Three proteins act on the transcriptional level, GgpR (Klähn et al., 2010b), LexA (Kizawa et al., 2016), and SigF (Huckauf et al., 2000; Marin et al., 2002). The sRNA IsaR1 interacts with ggpS mRNA at the postranscriptional level (Rübsam et al., 2018). The rapid activation of GG synthesis and its adjustment to the final salt content seem to be mainly regulated at the biochemical level via the cellular amount of inorganic ions (Novak et al., 2011).