Light-induced degradation of SPA2 via its N-terminal kinase domain is required for photomorphogenesis

• DOI: 10.1093/plphys/kiab156
• Publication Date: 2021-04-01T11:30:48Z
• Authors: Tobias Schenk; Laura Trimborn; Song Chen; Christian Schenkel; Ute Hoecker
• Keywords: Photomorphogenesis; Phytochrome; Subfunctionalization; Etiolation; Phytochrome A

Arabidopsis (Arabidopsis thaliana) CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) and members of the SUPPRESSOR OF PHYTOCHROMEA-105 (SPA) protein family form an E3 ubiquitin ligase that suppresses light signaling in darkness by polyubiquitinating positive regulators response. COP1/SPA is inactivated to allow photomorphogenesis proceed. Mechanisms inactivation include light-induced degradation SPA1 and, particular, SPA2, corresponding a particularly efficient COP1/SPA2 light. Here, we show SPA3 SPA4 proteins are stable light, indicating destabilization specific possibly related predominant function SPA2 dark-grown etiolating seedlings. involves cullin COP10-DEETIOLATED-DAMAGED-DNA BINDING PROTEIN (DDB1) CDD complex, besides COP1. Consistent with this finding, required DDB1-interacting Trp-Asp (WD)-repeat domain SPA2. Deletion N-terminus containing kinase led strong stabilization fully abolished This prevented seedling de-etiolation even very far-red blue reduced red through its N-terminal essential for exclusively destabilized phytochrome A However, deletion did not abolish SPA2-phytochrome interaction yeast nor vivo. Our mapping suggests there two interacting domains, WD-repeat domain. Conferring SPA2-phyA only via may thus lead inactivation.