Nitric Oxide Signaling System in Plant Innate Immunity - PAMP Signals in Plant Innate Immunity: Signal Perception and Transduction - page 316

a - Linolenic acid

NO Lipoxygense

Activation

13-hydroperoxy-linoleic acid

Allene oxide synthase
(AOS)

NO

Activation

12-13-Epoxy-octadeatrienoic acid (EOT)

Allene oxide cyclase
(AOC)

12-oxo-phytodienoic acid (OPDA)

12-oxo-phytodienoic
acid reductase 3
(OPR3)

NO

Activation

Jasmonic acid

Fig. 6.4 Role of NO in activation of jasmonic acid biosynthesis

6.8 Role of NO in Protein S -Nitrosylation

NO rapidly induces reversible S -nitrosylation of proteins involved in signal trans-
duction . The addition of an NO moiety to a cysteine (Cys) thiol to form an
S-nitrosothiol (SNO) is termed S-nitrosylation (Malik et al. 2011 ) . This redox-
based post-translational modifi cation is a key regulator of protein function in plant
immunity (Malik et al. 2011 ). Intracellular NO reacts with various proteins and
nonprotein thiols to form nitrosothiols (Stamler et al. 2001 ). Most of the NO-modifi ed
proteins are regulated by S -nitrosylation. S-Nitrosylation refers to the incorporation
of the NO moiety to a Cys sulfur atom to form a S-NO bond (Martinez-Ruiz and
Lamas 2004 ). Protein S-nitrosylation occurs at a single critical Cys residue by
oxygen-dependent chemical reactions or by the transfer of NO from a nitrosothiol
to a protein sulfhydryl group (Lindermayr et al. 2005 ). NO can react with sulfhydryl
groups on proteins, yielding SNOs, which lead to a change in protein function or