scholarly journals Convergent and Divergent Signaling in PAMP-Triggered Immunity and Effector-Triggered Immunity

2018 ◽  
Vol 31 (4) ◽  
pp. 403-409 ◽  
Author(s):  
Yujun Peng ◽  
Rowan van Wersch ◽  
Yuelin Zhang
Keyword(s):  
Plasma Membrane ◽  
Mitogen Activated Protein Kinase ◽  
Defense Gene Expression ◽  
Kinase Activation ◽  
Immune Receptors ◽  
Pathogen Effectors ◽  
Molecular Events ◽  
Protein Kinase Activation ◽  
Mitogen Activated Protein ◽  
Effector Triggered Immunity

Plants use diverse immune receptors to sense pathogen attacks. Recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors localized on the plasma membrane leads to PAMP-triggered immunity (PTI). Detection of pathogen effectors by intracellular or plasma membrane–localized immune receptors results in effector-triggered immunity (ETI). Despite the large variations in the magnitude and duration of immune responses triggered by different PAMPs or pathogen effectors during PTI and ETI, plasma membrane–localized immune receptors activate similar downstream molecular events such as mitogen-activated protein kinase activation, oxidative burst, ion influx, and increased biosynthesis of plant defense hormones, indicating that defense signals initiated at the plasma membrane converge at later points. On the other hand, activation of ETI by immune receptors localized to the nucleus appears to be more directly associated with transcriptional regulation of defense gene expression. Here, we review recent progress in signal transductions downstream of different groups of plant immune receptors, highlighting the converging and diverging molecular events.

scholarly journals N-terminally myristoylated Ras proteins require palmitoylation or a polybasic domain for plasma membrane localization.

1994 ◽  
Vol 14 (7) ◽  
pp. 4722-4730 ◽  
Author(s):  
K A Cadwallader ◽  
H Paterson ◽  
S G Macdonald ◽  
J F Hancock
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Membrane Targeting ◽  
Ras Proteins ◽  
Kinase Activation ◽  
Ras Protein ◽  
Oncogenic Ras ◽  
Protein Kinase Activation ◽  
Mitogen Activated Protein

Plasma membrane targeting of Ras requires CAAX motif modifications together with a second signal from an adjacent polybasic domain or nearby cysteine palmitoylation sites. N-terminal myristoylation is known to restore membrane binding to H-ras C186S (C-186 is changed to S), a mutant protein in which all CAAX processing is abolished. We show here that myristoylated H-ras C186S is a substrate for palmitoyltransferase, despite the absence of C-terminal farnesylation, and that palmitoylation is absolutely required for plasma membrane targeting of myristoylated H-ras. Similarly, the polybasic domain is required for specific plasma membrane targeting of myristoylated K-ras. In contrast, the combination of myristoylation plus farnesylation results in the mislocalization of Ras to numerous intracellular membranes. Ras that is only myristoylated does not bind with a high affinity to any membrane. The specific targeting of Ras to the plasma membrane is therefore critically dependent on signals that are contained in the hypervariable domain but can be supported by N-terminal myristoylation or C-terminal prenylation. Interestingly, oncogenic Ras G12V that is localized correctly to the plasma membrane leads to mitogen-activated protein kinase activation irrespective of the combination of targeting signals used for localization, whereas Ras G12V that is mislocalized to the cytosol or to other membranes activates mitogen-activated protein kinase only if the Ras protein is farnesylated.

N-terminally myristoylated Ras proteins require palmitoylation or a polybasic domain for plasma membrane localization

1994 ◽  
Vol 14 (7) ◽  
pp. 4722-4730
Author(s):  
K A Cadwallader ◽  
H Paterson ◽  
S G Macdonald ◽  
J F Hancock
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Membrane Targeting ◽  
Ras Proteins ◽  
Kinase Activation ◽  
Ras Protein ◽  
Oncogenic Ras ◽  
Protein Kinase Activation ◽  
Mitogen Activated Protein

Plasma membrane targeting of Ras requires CAAX motif modifications together with a second signal from an adjacent polybasic domain or nearby cysteine palmitoylation sites. N-terminal myristoylation is known to restore membrane binding to H-ras C186S (C-186 is changed to S), a mutant protein in which all CAAX processing is abolished. We show here that myristoylated H-ras C186S is a substrate for palmitoyltransferase, despite the absence of C-terminal farnesylation, and that palmitoylation is absolutely required for plasma membrane targeting of myristoylated H-ras. Similarly, the polybasic domain is required for specific plasma membrane targeting of myristoylated K-ras. In contrast, the combination of myristoylation plus farnesylation results in the mislocalization of Ras to numerous intracellular membranes. Ras that is only myristoylated does not bind with a high affinity to any membrane. The specific targeting of Ras to the plasma membrane is therefore critically dependent on signals that are contained in the hypervariable domain but can be supported by N-terminal myristoylation or C-terminal prenylation. Interestingly, oncogenic Ras G12V that is localized correctly to the plasma membrane leads to mitogen-activated protein kinase activation irrespective of the combination of targeting signals used for localization, whereas Ras G12V that is mislocalized to the cytosol or to other membranes activates mitogen-activated protein kinase only if the Ras protein is farnesylated.

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