Antagonistic peptide technology for functional dissection of CLE peptides revisited

Abstract

HighlightInformation collected using antagonistic peptide approaches can be very useful, but these approaches do not work in all cases and require insight on ligand-receptor interactions and peptide ligand structure.

Peptide Signaling Pathways in Vascular Differentiation

“…However, it often remains unclear which of the two successive periclinal formative divisions in the phloem lineage is affected, and it might very well turn out that one of them is essential for sieve element formation. Nonetheless, the CLE25 G6T phenotype strongly resembles the so-called Disturbed Protophloem Syndrome observed in backgrounds with elevated CLE45 signaling (Rodriguez-Villalon et al, 2014;Anne and Hardtke, 2017) and is consistent with simple dominant (rather than dominant negative) action of the CLE25 G6T version, as observed for other CLE peptides in other contexts (Czyzewicz et al, 2015), including CLE45 G6T in protophloem formation (Rodriguez-Villalon et al, 2014;Czyzewicz et al, 2015). This interpretation is also consistent with observations in pertinent receptor mutants.…”

A Cellular Insulator against CLE45 Peptide Signaling

“…However, redundant, conserved OPS homologs exist [9,31,36], and in pertinent loss-of-function double mutants the ops phenotype is aggravated [36]. Consistent with suppression of protophloem differentiation by CLE peptides [21,27,28] and a role for OPS in antagonizing CLE signaling, these double mutants display substantial delays and frequent failures in protophloem differentiation [36]. Although the strong systemic impact of discontinuous protophloem strands on overall root meristem activity [24,28] renders interpretation of these phenotypes difficult, the observed differentiation delays could be viewed as reduced capacity of developing PPSEs to escape the meristematic stage.…”

“…brx or ops defects can be rescued by bam3 second site mutations [8,18,21]. Conversely, CLE45 peptide application or dosage increase suppresses PPSE differentiation, suggesting a role for autocrine peptide signaling in protophloem formation [8,18,27,28]. Moreover, CLE45 signaling through BAM3 is quantitatively limited by the CLV2jCRN heteromer [21], which is why crn mutants are resistant to CLE45.…”

CLE19expressed in the embryo regulates both cotyledon establishment and endosperm development inArabidopsis

“…When endogenous regulatory elements are used in this type of study, it is expected that the antagonistic peptides produced may act in situ to interfere with the signal transduction pathways involved. One study published in this issue showed that synthetic CLE peptides with a G6T substitution are less effective than wild-type peptides in seedling treatments in vitro ( Czyzewicz et al , 2015 ). This is expected since it has been shown in CLV3 that the G6 residue is critical for the CLV3 function: (i) a clv3-1 mutant with a severe defect in SAM homeostasis was caused by a substitution in G6 ( Fletcher et al , 1999 ); (ii) pCLV3:CLV3 G6A :tCLV3 is one of the least effective constructs in complementing the clv3-2 mutant ( Song et al , 2012 ); and (iii) no transgenic plants carrying the pCLV3:CLV3 G6T :tCLV3 construct showed complete complementation of the clv3-2 phenotype ( Song et al , 2013 ).…”