Curvature thylakoid 1 proteins modulate prolamellar body morphology and promote organized thylakoid biogenesis in Arabidopsis thaliana

Omar Sandoval-Ibáñez, Anurag Sharma, Michał Bykowski, Guillem Borràs-Gas, James B.Y.H. Behrendorff, Silas Mellor, Klaus Qvortrup, Julian C. Verdonk, Ralph Bock, Łucja Kowalewska*, Mathias Pribil

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The term “de-etiolation” refers to the light-dependent differentiation of etioplasts to chloroplasts in angiosperms. The underlying process involves reorganization of prolamellar bodies (PLBs) and prothylakoids into thylakoids, with concurrent changes in protein, lipid, and pigment composition, which together lead to the assembly of active photosynthetic complexes. Despite the highly conserved structure of PLBs among land plants, the processes that mediate PLB maintenance and their disassembly during de-etiolation are poorly understood. Among chloroplast thylakoid membrane-localized proteins, to date, only Curvature thylakoid 1 (CURT1) proteins were shown to exhibit intrinsic membrane-bending capacity. Here, we show that CURT1 proteins, which play a critical role in grana margin architecture and thylakoid plasticity, also participate in de-etiolation and modulate PLB geometry and density. Lack of CURT1 proteins severely perturbs PLB organization and vesicle fusion, leading to reduced accumulation of the light-dependent enzyme protochlorophyllide oxidoreductase (LPOR) and a delay in the onset of photosynthesis. In contrast, overexpression of CURT1A induces excessive bending of PLB membranes, which upon illumination show retarded disassembly and concomitant overaccumulation of LPOR, though without affecting greening or the establishment of photosynthesis. We conclude that CURT1 proteins contribute to the maintenance of the paracrystalline PLB morphology and are necessary for efficient and organized thylakoid membrane maturation during de-etiolation.

Original languageEnglish
Article numbere2113934118
JournalProceedings of the National Academy of Sciences of the United States of America
Volume118
Issue number42
DOIs
Publication statusPublished - 19 Oct 2021

Keywords

  • Chloroplast biogenesis
  • CURT1
  • De-etiolation
  • Photosynthesis
  • Prolamellar bodies

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