Regulation of plant peptide hormones and growth factors by post‐translational modification

Abstract

The number, diversity and significance of peptides as regulators of cellular differentiation, growth, development and defence of plants has long been underestimated. Peptides have now emerged as an important class of signals for cell-to-cell communication over short distances, and also for long-range signalling. We refer to these signalling molecules as peptide growth factors and peptide hormones, respectively. As compared to remarkable progress with respect to the mechanisms of peptide perception and signal transduction, the biogenesis of signalling peptides is still in its infancy. This review focuses on the biogenesis and activity of small post-translationally modified peptides. These peptides are derived from inactive pre-pro-peptides of approximately 70-120 amino acids. Multiple post-translational modifications (PTMs) may be required for peptide maturation and activation, including proteolytic processing, tyrosine sulfation, proline hydroxylation and hydroxyproline glycosylation. While many of the enzymes responsible for these modifications have been identified, their impact on peptide activity and signalling is not fully understood. These PTMs may or may not be required for bioactivity, they may inactivate the peptide or modify its signalling specificity, they may affect peptide stability or targeting, or its binding affinity with the receptor. In the present review, we will first introduce the peptides that undergo PTMs and for which these PTMs were shown to be functionally relevant. We will then discuss the different types of PTMs and the impact they have on peptide activity and plant growth and development. We conclude with an outlook on the open questions that need to be addressed in future research.

Sialoglycans and genetically engineered plants

“…Recently different posttranslational modifications (PTMs) have been reported for peptide maturation and activation, including proteolytic processing, tyrosine sulfation, proline hydroxylation, and hydroxyproline glycosylation [7] in plants. While glycan epitopes of human complex Nglycans are often targets of lectins important for cell-cell communication, the role of plant N-glycans finds importance in protein folding, and other biological functions including salt stress responses, cellulose biosynthesis, microtubule association, and biogenesis of several receptor-like kinases [8].…”

Identification and Functional Investigation of Genome‐Encoded, Small, Secreted Peptides in Plants

“…Choosing the peptide sequence to be synthesized can be a difficult task, especially for novel SSP genes that do not belong to established and previously investigated families. In vivo peptide maturation (i.e., peptidase processing and addition of side chain modifications) in the ER (i.e., the secretory pathway) is generally poorly understood (Olsson et al, 2018;Stührwohldt & Schaller, 2019;Stührwohldt, Schardon, Stintzi, & Schaller, 2017). For a novel SSP gene, it is therefore advisable to initially select and synthesize several staggered peptides based on gene alignments and/or HMMs (Fig.…”

The biogenesis of CLEL peptides involves several processing events in consecutive compartments of the secretory pathway

“…Complementing the activity of the classical phytohormones, peptide hormones and growth factors are now recognized as an important class of signaling molecules for long-range signaling and for cell-to-cell communication over short distances, respectively (Oh et al, 2018;Stührwohldt and Schaller, 2019). In Arabidopsis thaliana (hereafter 'Arabidopsis'), there are more than 1000 genes potentially encoding signaling peptides, apparently involved in all aspects of plant growth and development (Lease and Walker, 2006;Ghorbani et al, 2015;Tavormina et al, 2015).…”

“…The biogenesis of these signaling molecules, on the other hand, is still poorly understood. This is particularly true for the large group of signaling peptides that depend on a series of post-translational modifications (PTMs) for maturation and activation (Matsubayashi, 2014;Stührwohldt and Schaller, 2019).…”