Plant Protein Termini: Their Generation, Modification and Function

Diverse protein forms (or proteoforms) can arise from a single gene and together constitute a vast proteome complexity that governs cellular processes. Proteoforms with distinct protein termini can stem from diverse pre-, co- and post-translational mechanisms. Examples of pre-translational mechanisms are alternative splicing or translation initiation sites that result in different protein termini. Co-translational mechanisms include N-terminal methionine excision and the modification of nascent peptides. The above-mentioned mechanisms are ubiquitous and alter eukaryotic protein N-termini. At a post-translational level, proteases can generate novel N- and C-termini and can, besides general turnover, give rise to protein fragments with altered function, stability or localization (e.g. signaling peptides). Protein termini can be further trimmed by amino- or carboxypeptidases, post-translationally modified or recognized by specific E3 ubiquitin ligases termed N-recognins and be targeted for proteasomal degradation by the N-degron pathway. In summary, protein termini are highly dynamic and crucial determinants of protein function, regulation and stability.

In plants, our understanding of the extent and functional implications of protein termini and their corresponding proteoforms is still in its infancy. Proteome-wide characterization of protein N-termini and/or C-termini is key to uncover proteins subject to pre-, co- and post-translational modifications or identify substrates of peptidases and substrates of the N-degron pathway. Besides systematic proteomic studies, biochemical and genetic approaches are instrumental to determine the mode-of-action and role of proteases, amino/carboxypeptidases, N-terminal modifying enzymes or N-recognins in plant physiological processes. In addition, studying the functional relevance of proteoforms with different (modified) protein termini requires dedicated studies. An overarching goal of this research topic is to understand how different enzymatic regulatory processes acting on protein termini cooperate and together steer cellular signaling in plants.

We seek submissions around:
• Proteomic studies identifying N- and/or C-termini in plants (for instance peptidase or N-degron pathway substrates, N-terminal modifications)
• Biochemical and genetic studies of peptidases or enzymes modifying/recognizing protein termini
• Functional studies of proteoforms with altered protein termini (truncations, extensions, modifications) arising from any regulatory process (alternative splicing, translation initiation, N-terminal modifications, peptidase processing, ..)
• Methods to study the generation, stability and modification status of protein termini
• Systematic studies or perspectives linking fields of peptidase processing, post-translational modifications of protein termini and/or degradation

Please note: descriptive studies that solely report lists of differentially abundant proteins are outside the scope of the journal and will not be considered for review. Such datasets must be accompanied by hypothesis-driven, physiologically relevant functional characterization of candidate proteins/proteoforms of interest.