BIG enhances Arg/N-degron pathway-mediated protein degradation to regulate Arabidopsis hypoxia responses and suberin deposition

A - Papers appearing in refereed journals

Zhang, H., Rundle, C., Winter, N., Miricescu, A., Mooney B. C., Bachmair, A., Graciet, E. and Theodoulou, F. L. 2024. BIG enhances Arg/N-degron pathway-mediated protein degradation to regulate Arabidopsis hypoxia responses and suberin deposition. The Plant Cell. p. koae117. https://doi.org/10.1093/plcell/koae117

AuthorsZhang, H., Rundle, C., Winter, N., Miricescu, A., Mooney B. C., Bachmair, A., Graciet, E. and Theodoulou, F. L.
Abstract

BIG/DARK OVEREXPRESSION OF CAB1/TRANSPORT INHIBITOR RESPONSE3 is a 0.5-MDa protein associated with multiple functions in Arabidopsis (Arabidopsis thaliana) signalling and development. However, the biochemical functions of BIG are unknown. We investigated a role for BIG in the Arg/N-degron pathways, in which substrate protein fate is influenced by the N-terminal (Nt) residue. We crossed a big loss-of-function allele to two N-degron pathway E3 ligase mutants, proteolysis6 (prt6) and prt1, and examined the stability of protein substrates. Stability of model substrates was enhanced in prt6-1 big-2 and prt1-1 big-2 relative to the respective single mutants and the abundance of the PRT6 physiological substrates, HYPOXIA-RESPONSIVE ERF2 (HRE2) and VERNALIZATION2 (VRN2) was similarly increased in prt6 big double mutants. Hypoxia marker expression was enhanced in prt6 big double mutants; this constitutive response required arginyltransferase activity and RAP-type ERFVII transcription factors. Transcriptomic analysis of roots not only demonstrated increased expression of multiple hypoxia-responsive genes in the double mutant relative to prt6, but also revealed other roles for PRT6 and BIG, including regulation of suberin deposition through both ERFVII-dependent and independent mechanisms, respectively. Our results show that BIG acts together with PRT6 to regulate the hypoxia response and broader processes in Arabidopsis.

KeywordsProteolosis6 (PRT6) ; Suberin; Ubiquitin amino-end recognizing protein box (UBR box) ; Proteostasis; Vernalisation (VRN2)
Year of Publication2024
JournalThe Plant Cell
Journal citationp. koae117
Digital Object Identifier (DOI)https://doi.org/10.1093/plcell/koae117
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeTailoring Plant Metabolism ISP
Green Engineering
Publisher's version
Output statusPublished
Publication dates
Online12 Apr 2024
Publication process dates
Accepted21 Mar 2024
PublisherAmerican Society of Plant Biologists (ASPB)
ISSN1532-298X

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