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SUMOylation of phytochrome-B negatively regulates light-induced signaling in Arabidopsis thaliana

Sadanandom, A.; Ádám, É; Orosa, B.; Viczián, A.; Klose, C.; Zhang, C.; Josse, E.M.; Kozma-Bognár, L.; Nagy, F.


É Ádám

B. Orosa

A. Viczián

C. Klose

C. Zhang

E.M. Josse

L. Kozma-Bognár

F. Nagy


The red/far red light absorbing photoreceptor phytochrome-B (phyB) cycles between the biologically inactive (Pr, λmax, 660 nm) and active (Pfr; λmax, 730 nm) forms and functions as a light quality and quantity controlled switch to regulate photomorphogenesis in Arabidopsis. At the molecular level, phyB interacts in a conformation-dependent fashion with a battery of downstream regulatory proteins, including PHYTOCHROME INTERACTING FACTOR transcription factors, and by modulating their activity/abundance, it alters expression patterns of genes underlying photomorphogenesis. Here we report that the small ubiquitin-like modifier (SUMO) is conjugated (SUMOylation) to the C terminus of phyB; the accumulation of SUMOylated phyB is enhanced by red light and displays a diurnal pattern in plants grown under light/dark cycles. Our data demonstrate that (i) transgenic plants expressing the mutant phyBLys996Arg-YFP photoreceptor are hypersensitive to red light, (ii) light-induced SUMOylation of the mutant phyB is drastically decreased compared with phyB-YFP, and (iii) SUMOylation of phyB inhibits binding of PHYTOCHROME INTERACTING FACTOR 5 to phyB Pfr. In addition, we show that OVERLY TOLERANT TO SALT 1 (OTS1) de-SUMOylates phyB in vitro, it interacts with phyB in vivo, and the ots1/ots2 mutant is hyposensitive to red light. Taken together, we conclude that SUMOylation of phyB negatively regulates light signaling and it is mediated, at least partly, by the action of OTS SUMO proteases.


Sadanandom, A., Ádám, É., Orosa, B., Viczián, A., Klose, C., Zhang, C., …Nagy, F. (2015). SUMOylation of phytochrome-B negatively regulates light-induced signaling in Arabidopsis thaliana. Proceedings of the National Academy of Sciences, 112(35), 11108-11113.

Journal Article Type Article
Acceptance Date Jul 16, 2015
Online Publication Date Aug 17, 2015
Publication Date Sep 1, 2015
Deposit Date Sep 9, 2015
Journal Proceedings of the National Academy of Sciences
Print ISSN 0027-8424
Electronic ISSN 1091-6490
Publisher National Academy of Sciences
Peer Reviewed Peer Reviewed
Volume 112
Issue 35
Pages 11108-11113
Keywords Photoreceptor, Phytochrome, Sumoylation, Signaling, Photomorphogenesis.