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Nucleo‐plastidic PAP 8/ pTAC 6 couples chloroplast formation with photomorphogenesis
Author(s) -
Liebers Monique,
Gillet FrançoisXavier,
Israel Abir,
Pounot Kevin,
Chambon Louise,
Chieb Maha,
Chevalier Fabien,
Ruedas Rémi,
Favier Adrien,
Gans Pierre,
Boeri Erba Elisabetta,
Cobessi David,
Pfannschmidt Thomas,
Blanvillain Robert
Publication year - 2020
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2020104941
Subject(s) - biology , photomorphogenesis , chloroplast , microbiology and biotechnology , biochemistry , arabidopsis , gene , mutant
The initial greening of angiosperms involves light activation of photoreceptors that trigger photomorphogenesis, followed by the development of chloroplasts. In these semi‐autonomous organelles, construction of the photosynthetic apparatus depends on the coordination of nuclear and plastid gene expression. Here, we show that the expression of PAP 8, an essential subunit of the plastid‐encoded RNA polymerase ( PEP ) in Arabidopsis thaliana , is under the control of a regulatory element recognized by the photomorphogenic factor HY 5. PAP 8 protein is localized and active in both plastids and the nucleus, and particularly required for the formation of late photobodies. In the pap8 albino mutant, phytochrome‐mediated signalling is altered, degradation of the chloroplast development repressors PIF 1/ PIF 3 is disrupted, HY 5 is not stabilized, and the expression of the photomorphogenesis regulator GLK 1 is impaired. PAP 8 translocates into plastids via its targeting pre‐sequence, interacts with the PEP and eventually reaches the nucleus, where it can interact with another PEP subunit pTAC 12/ HMR / PAP 5. Since PAP 8 is required for the phytochrome B‐mediated signalling cascade and the reshaping of the PEP activity, it may coordinate nuclear gene expression with PEP ‐driven chloroplastic gene expression during chloroplast biogenesis.