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

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

NO-vermittelte Modifizierung von Nukleären Proteinen: S-Nitrosylierung von <i>Arabidopsis</i> HD2-Proteinen

A map of NO-regulated nuclear candidates (117 proteins), from pathogen-treated Arabidopsis cell cultures was generated. S-nitrosylation of HD2C resulted in release of its zinc ion, which might affect its interaction with other proteins (identified by Co-immuonoprecipitation). Complementation of HD2C-C269/272H to hd2c mutant associated with lower inhibition of rosette growth by abscisic acid in compare to wild type. According these data S-nitrosylation might inhibit putative positive role of HD2C.Eine Übersicht über NO-regulierte 117 Kernproteine aus Pathogen-behandelten Arabidopsis thaliana Zellkulturen wurde erstellt. Interessanterweise führt die S-Nitrosylierung von HD2C zur Freisetzung seines Zinkions, was möglicherweise die Interaktion mit anderen Proteinen beeinflusst. Außerdem zeigt eine HD2C-ko Linie, die mit einem HD2C-C269/272H Konstukt komplementiert wurde, nach Abszisinsäure-Behandlung eine geringere Hemmung des Rosettenwachstums im Vergleich zum Wildtyp. Diese Daten deuten darauf hin, dass diese Cysteinreste für die Funktion der HD2C von Bedeutung sind und dass deren S-Nitrosylierung die positive Rolle von HD2C bei Abszisinsäure-abhängigen Stoffwechselwegen abschaltet