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ABC1K proteins of Arabidopsis Plastoglobules regulate thylakoid membrane remodeling in chloroplasts
Author(s) -
Espinoza Corral Roberto,
Lundquist Peter
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.00400
Subject(s) - thylakoid , arabidopsis , chloroplast , biology , twin arginine translocation pathway , microbiology and biotechnology , protein kinase a , photosystem , phosphorylation , biochemistry , mutant , gene
The chloroplast's thylakoid membrane houses photosynthetic light‐harvesting. This process requires pigments and electron carriers for the transport of electrons across the photosystems II and I. Thylakoid membranes undergo remodeling and dismantling of their protein and lipid composition upon stresses and developmental stage transitions such as senescence. Under such circumstances, plastoglobules lipid droplets attached to thylakoids increase in number and size accumulating a plethora of lipids assisting the remodeling of membranes. Contiguous to the thylakoid membrane, plastoglobules consist of a neutral lipid core and a glycerolipid monolayer surface. The protein portion of plastoglobules is a set of 30 proteins segregated from the thylakoid membranes. So far, the molecular mechanisms by which plastoglobules change with the concomitant thylakoid dismantling and remodeling are unknown. However, it is assumed that these processes are regulated by the activity of the ancient protein kinase family ABC1K ( a ctivity of bc1 complex k inase) being the second most abundant proteins in isolated plastoglobules after fribrillins. Here we show that the kinase activity of isolated plastoglobules changes under high light stress along with the dismantling of thylakoid membranes. Additionally, we characterized the activity of one member of this family confirming its kinase activity in‐vitro . Furthermore, Arabidopsis knock‐out mutant plants for this kinase protein display a delay in transitioning into senescence, a process requiring thylakoid dismantling. Finally, we showed that the non‐phosphorylated version of a plastoglobular protein rescues the knockout mutant phenotype in Arabidopsis plants while the phospho‐mimicking version fails, implying that indeed phosphorylation can impact the function of plastoglobule proteins in‐vivo . Together our results provide further evidence for the activity of the ABC1K protein family as well as highlighting the role of protein phosphorylation in thylakoid membrane remodeling.