Nitric oxide donor-mediated inhibition of phosphorylation shows that light-mediated degradation of photosystem II D1 protein and phosphorylation are not tightly linked

Abstract

An outcome of the photochemistry during oxygenic photosynthesis is the rapid turn over of the D1 protein in the light compared to the other proteins of the photosystem II (PS II) reaction center. D1 is a major factor of PS II instability and its replacement a primary event of the PS II repair cycle. D1 also undergoes redox-dependent phosphorylation prior to its degradation. Although it has been suggested that phosphorylation modulates D1 metabolism, reversible D1 phosphorylation was reported not to be essential for PS II repair in Arabidopsis. Thus, the involvement of phosphorylation in D1 degradation is controversial. We show here that nitric oxide donors inhibit in vivo phosphorylation of the D1 protein in Spirodela without inhibiting degradation of the protein. Thus, D1 phosphorylation is not tightly linked to D1 degradation in the intact plant.

Effects of exogenous nitric oxide on photosynthesis

“…Concerning localization, NO production was proved to occur in root mitochondria (Planchet et al 2005), peroxisomes (Barroso et al 1999), and plasma membrane (Stohr et al 2001). Further, nonenzymatic NO formation was proved in acidic and reducing environments, such as the apoplasm (Bethke et al 2004) and plastids (Cooney et al 1994).…”

“…Ördög et al (2013) showed, that NO is able to hamper the activity of the plasma membrane H + -ATPase in bean guard cells. Booij-James et al (2009) demonstrated that NO donors, 3-morpholinosydnonimine (which is ONOOdonor as well) and S-nitrosocysteine, inhibited in vivo phosphorylation of the D1 protein in Spirodella without inhibiting degradation of the protein. Thus, the authors demonstrated that D1 phosphorylation is not highly linked to D1 degradation.…”

Friend or Foe? Exploring the Factors that Determine the Difference Between Positive and Negative Effects on Photosynthesis in Response to Insect Herbivory

“…D1 is a target of at least five post-translational modifications during its life cycle, including N-acetylation, palmitoylation and phosphorylation (Edelman & Mattoo, 2008). One or more of these post-translational modifications could potentially alter protein degradation kinetics, although the use of nitric oxide donors to inhibit in vivo phosphorylation of the D1 protein suggested that redox-dependent phosphorylation and D1 degradation in plants are not linked events (Booij-James et al, 2009). The DegP and FtsH proteases have been shown to be involved in D1 degradation in vitro (Haussuhl et al, 2001;Kanervo et al, 2003;Lindahl et al, 2000).…”