Effect of nitric oxide on gene transcription - S-nitrosylation of nuclear proteins

Abstract

Nitric oxide (NO) plays an important role in many different physiological processes in plants. It mainly acts by post-translationally modifying proteins. Modification of cysteine residues termed as S-nitrosylation is believed to be the most important mechanism for transduction of bioactivity of NO. The first proteins found to be nitrosylated were mainly of cytoplasmic origin or isolated from mitochondria and peroxisomes. Interestingly, it was shown that redox-sensitive transcription factors are also nitrosylated and that NO influences the redox-dependent nuclear transport of some proteins. This implies that NO plays a role in regulating transcription and/or general nuclear metabolism which is a fascinating new aspect of NO signaling in plants. In this review, we will discuss the impact of S-nitrosylation on nuclear plant proteins with a focus on transcriptional regulation, describe the function of this modification and draw also comparisons to the animal system in which S-nitrosylation of nuclear proteins is a well characterized concept.

Keywords: nitric oxide; nuclear proteins; post-translational modification; protein S-nitrosylation; redox-modification.

FIGURE 1

S-nitrosylation can affect gene transcription in several ways. Upon S-nitrosylation proteins can change their subcellular localization which may lead to either import in (A) or export out (B) of the nucleus (Qu et al., 2007; Malik et al., 2010). Alternatively, S-nitrosylation is also described to alter DNA-binding activity of certain proteins (C,D; Serpa et al., 2007; Lindermayr et al., 2010; Sha and Marshall, 2012). Additionally, SNO-formation can lead to association/dissociation of macromolecular complexes which may result in dissociation from chromatin (E; Nott et al., 2008). Various combinations including indirect regulation are also conceivable (F).