Cutting in the middleman: hidden substrates at the interface between proteases and plant development

Abstract

Contents Summary 916 I. Introduction 916 II. DEK1: towards identification of protease substrates 917 III. Separases: when proteolytic modules attain nonproteolytic functions 918 IV. The peculiar case of a nonredundant subtilisin 919 V. Towards a solution to the protease redundancy problem 920 VI. Matters arising and closing remarks 921 Acknowledgements 921 References 921 SUMMARY: Proteases are integral components of proteome remodelling networks that regulate turnover of proteins and expand their functional diversity. Accumulating evidence highlights the importance of proteases as being central hubs of developmental programs. Yet the molecular pathways that many proteases act on, their natural substrates and their putative nonproteolytic functions remain largely elusive. Here, we discuss recent findings on proteases with functions that converge into plant development regulation, such as DEFECTIVE KERNEL 1 (DEK1), separase and subtilisins, to highlight conspicuous but unexplored aspects of protease biology. We also suggest an exploratory framework for addressing protease functions.

Domain swap between two type‐II metacaspases defines key elements for their biochemical properties

“…Furthermore, reactive oxygen signaling mediated by respiratory burst oxidase homolog (RBOH) proteins along with the transmembrane receptor kinase signaling by the extracellular peptide RALF (rapid alkalinization factor 1) can be integrated through the AHAs to generate apo pH changes (reviewed by Mangano et al ., ). In this context, it is interesting to note that an AHA has been identified among potential targets for AtMC9 (Tsiatsiani et al ., ), whereas the degradome for the Arabidopsis separase, which was reported to relate structurally to metacaspases (Liu and Moschou, ), also contain two AHAs (Liu et al ., ). These results thus indicate that AHAs could be direct targets for type‐II MCs and may hint at possible feedback interactions between the MC9 class of type‐II MCs and AHA functions.…”

The Role of Proteases in Determining Stomatal Development and Tuning Pore Aperture: A Review

“…CRSP negatively regulates stomatal development under high CO 2 concentration by processing the EPF2 precursor [39]. This processing results to blockage of the asymmetric divisions of the MMCs [42].…”

The plant N‐degron pathways of ubiquitin‐mediated proteolysis

“…In addition to Arg, other amino‐acids or modified forms also serve as primary destabilizing residues for direct recognition by E3 ligase N‐recognins (Figure A) (Varshavsky ). Physiological substrates with destabilizing residues have been identified, but in many cases biochemical components of the pathway and diversity of destabilizing residues were initially determined with artificial substrates using the ubiquitin fusion technique (Bachmair et al ) that allows the generation of a stoichiometric mixture of stable and test proteoforms (in this context polypeptides produced after proteolytic cleavage events; Liu and Moschou ) following constitutive deubiquitinase activity, whose relative stabilities can then be monitored (Bachmair et al ; Graciet et al ). Analysis of the half‐lives of artificial N‐degron pathway substrates in plants ( Arabidopsis thaliana , hereafter Arabidopsis and Nicotiana tabacum , tobacco) showed that destabilizing residue identity is conserved with higher animals, including the observation of Nt‐Cys as a destabilizing residue (Graciet et al ).…”