Oxygen-dependent proteolysis regulates the stability of angiosperm polycomb repressive complex 2 subunit VERNALIZATION 2

• Published in: Nature communications Vol. 9; no. 1; pp. 5438 - 11
• Main Authors: Gibbs, Daniel J., Tedds, Hannah M., Labandera, Anne-Marie, Bailey, Mark, White, Mark D., Hartman, Sjon, Sprigg, Colleen, Mogg, Sophie L., Osborne, Rory, Dambire, Charlene, Boeckx, Tinne, Paling, Zachary, Voesenek, Laurentius A. C. J., Flashman, Emily, Holdsworth, Michael J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21-12-2018; Nature Publishing Group; Nature Portfolio
• Subjects: 38/15; 38/70; 38/77; 45/91; 631/449/2675; 631/449/448/2189; 82/1; 82/29; 82/58; 82/80; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins - metabolism; Carrier Proteins - metabolism; Cold Temperature; Cold tolerance; Control stability; DNA-Binding Proteins; Epigenetics; Eukaryotes; Evolution, Molecular; Flowering; Gene duplication; Gene Expression Regulation, Plant; Homology; Humanities and Social Sciences; Hypoxia; Hypoxia - metabolism; multidisciplinary; Nuclear Proteins - metabolism; Oxygen; Oxygen - metabolism; Plants (botany); Polycomb group proteins; Polycomb Repressive Complex 2 - metabolism; Post-translation; Proteolysis; Science; Science (multidisciplinary); Transcription; Vernalization
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-07875-7

The polycomb repressive complex 2 (PRC2) regulates epigenetic gene repression in eukaryotes. Mechanisms controlling its developmental specificity and signal-responsiveness are poorly understood. Here, we identify an oxygen-sensitive N-terminal (N-) degron in the plant PRC2 subunit VERNALIZATION(VRN) 2, a homolog of animal Su(z)12, that promotes its degradation via the N-end rule pathway. We provide evidence that this N-degron arose early during angiosperm evolution via gene duplication and N-terminal truncation, facilitating expansion of PRC2 function in flowering plants. We show that proteolysis via the N-end rule pathway prevents ectopic VRN2 accumulation, and that hypoxia and long-term cold exposure lead to increased VRN2 abundance, which we propose may be due to inhibition of VRN2 turnover via its N-degron. Furthermore, we identify an overlap in the transcriptional responses to hypoxia and prolonged cold, and show that VRN2 promotes tolerance to hypoxia. Our work reveals a mechanism for post-translational regulation of VRN2 stability that could potentially link environmental inputs to the epigenetic control of plant development.
VRN2 is a Polycomb Repressive Complex 2 subunit, best known as a regulator of vernalization that accumulates during prolonged cold. Here Gibbs
et al
. show that VRN2 is degraded via the N-end rule pathway, which  prevents ectopic accumulation of VRN2 in the absence of appropriate environmental stimuli.