Review Article

Reactive Oxygen Species in the Signaling and Adaptation of Multicellular Microbial Communities

Figure 2

Hypothesis on the effect of H2O2 balance on induction of ammonia signaling.  Left: predictions of changes in H2O2 concentration in cytosol and mitochondria of wild type and three oxidative-stress-defense-deficient strains based on reactions catalyzed by three main stress defense enzymes, cytosolic and mitochondrial superoxide dismutase Sod1p and Sod2p, respectively, and cytosolic catalase Ctt1p. Orange arrows indicate predicted H2O2 gradient between mitochondria and cytosol in wild-type strain and the three mutants. H2O2 gradient in wild-type cells is proposed on the basis of the prediction that mitochondria are the major site of ROS production in starving respiring cells from acidic-phase colonies. Right: the balances compare the mitochondrial-cytosolic H2O2-homeostasis of the particular mutant strain and the wild-type colony. The H2O2 imbalance towards the higher H2O2 concentration in the cytosol abolishes the induction of ammonia signaling and proper colony development and differentiation.
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