Plant cysteine oxidases are dioxygenases that directly enable arginyl transferase-catalysed arginylation of N-end rule targets

Abstract

Crop yield loss due to flooding is a threat to food security. Submergence-induced hypoxia in plants results in stabilization of group VII ETHYLENE RESPONSE FACTORs (ERF-VIIs), which aid survival under these adverse conditions. ERF-VII stability is controlled by the N-end rule pathway, which proposes that ERF-VII N-terminal cysteine oxidation in normoxia enables arginylation followed by proteasomal degradation. The PLANT CYSTEINE OXIDASEs (PCOs) have been identified as catalysts of this oxidation. ERF-VII stabilization in hypoxia presumably arises from reduced PCO activity. We directly demonstrate that PCO dioxygenase activity produces Cys-sulfinic acid at the N terminus of an ERF-VII peptide, which then undergoes efficient arginylation by an arginyl transferase (ATE1). This provides molecular evidence of N-terminal Cys-sulfinic acid formation and arginylation by N-end rule pathway components, and a substrate of ATE1 in plants. The PCOs and ATE1 may be viable intervention targets to stabilize N-end rule substrates, including ERF-VIIs, to enhance submergence tolerance in agriculture.

Emerging branches of the N-end rule pathways are revealing the sequence complexities of N-termini dependent protein degradation

“…Conversely, in plants N-terminal cysteine oxidation is enzymatically catalyzed in the presence of molecular oxygen (White et al 2017). In depth D r a f t discussions regarding the roles of N-end rule protein degration in plants can be found in a number of recent reviews (Dissmeyer et al 2017;Gibbs et al 2016;van Dongen and Licausi 2015). As yeast lacks NO-synthases and N-terminal cysteine oxidases, N-terminal cysteines are stabilizing residues in these organisms.…”

Group VII Ethylene Response Factors in Arabidopsis: Regulation and Physiological Roles

“…In addition, in vitro evidence suggests that PCOs influence ERF-VII in vivo turnover by direct Cys2 oxidation. Purified recombinant PCO enzymes consume molecular oxygen in the presence of either L-Cys or synthetic peptides corresponding to AtRAP2.12 N terminus (Weits et al, 2014) and catalyze the reaction of N-terminal Cys to Cys-sulfinic acid (CysO 2 ; White et al, 2017). A recombinant plant ATE1 enzyme can also conjugate Arg to a synthetic NH 2 -CGGAIISDFI-COOH peptide, derived from the AtRAP2.12 N terminus, only in the presence of both PCO and oxygen.…”

“…Arginyl transferase (ATE) enzymes conjugate oxidized Cys (*Cys) to Arg, which in turn recruits the Arg-specific N-recognin PRT6 (Garzó n et al, 2007), an N-end rule pathway-specialized E3 ubiquitin ligase that labels the substrate for degradation through the 26S proteasome (see Box 1 for additional details of the pathway). Cys oxidation can be promoted by specific thiol oxygenases called plant Cys oxidases (PCOs): In the presence of oxygen, PCOs convert Cys into Cys-sulfinic acid, which acts as an ATE substrate (White et al, 2017). Therefore, PCOs target ERF-VII proteins to the proteasome in an oxygen-dependent fashion.…”

Genomic and phenotypic divergence unveil microgeographic adaptation in the Amazonian hyperdominant tree Eperua falcata Aubl. (Fabaceae)

“…Topography-linked microgeographic patchiness is likely driven by a bundle of abiotic and biotic factors (including soil types (Misiewicz and Fine 2014), water-logging and flooding events, water availability (Clark et al 1999), seasonal soil drought (Markewitz et al 2010) We notably detected several genes involved in plant response to stress near outlier SNPs. For example, we detected a glutaredoxin-C11 (predgene_010110) involved in managing the level of reactive oxygen species (ROS) in plant cells (Mittler et al 2004), a H 2 O 2 -responsive gene encoding a metallopeptidase M24 family protein which is up-regulated under stress in Arabidopsis thaliana (Ordoñez et al 2014), and a gene encoding a plant cysteine oxidase 4-like (predgene 003921) involved in response to flooding and soil hypoxia (Weits et al 2014;White et al 2017). Oxidative stress is very common in bottomlands, where water-logging and seasonal flooding events cause soil hypoxia and oxygen deprivation in root All rights reserved.…”