Post-translational coordination of chlorophyll biosynthesis and breakdown by BCMs maintains chlorophyll homeostasis during leaf development

Nat Commun. 2020 Mar 20;11(1):1254. doi: 10.1038/s41467-020-14992-9.


Chlorophyll is indispensable for life on Earth. Dynamic control of chlorophyll level, determined by the relative rates of chlorophyll anabolism and catabolism, ensures optimal photosynthesis and plant fitness. How plants post-translationally coordinate these two antagonistic pathways during their lifespan remains enigmatic. Here, we show that two Arabidopsis paralogs of BALANCE of CHLOROPHYLL METABOLISM (BCM) act as functionally conserved scaffold proteins to regulate the trade-off between chlorophyll synthesis and breakdown. During early leaf development, BCM1 interacts with GENOMES UNCOUPLED 4 to stimulate Mg-chelatase activity, thus optimizing chlorophyll synthesis. Meanwhile, BCM1's interaction with Mg-dechelatase promotes degradation of the latter, thereby preventing chlorophyll degradation. At the onset of leaf senescence, BCM2 is up-regulated relative to BCM1, and plays a conserved role in attenuating chlorophyll degradation. These results support a model in which post-translational regulators promote chlorophyll homeostasis by adjusting the balance between chlorophyll biosynthesis and breakdown during leaf development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Chlorophyll / biosynthesis*
  • Chloroplasts / metabolism
  • Chloroplasts / ultrastructure
  • Conserved Sequence
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / metabolism*
  • Enzymes / metabolism
  • Epistasis, Genetic
  • Gene Expression Regulation, Plant
  • Homeostasis*
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Models, Biological
  • Plant Leaves / genetics
  • Plant Leaves / growth & development*
  • Plant Leaves / metabolism*
  • Protein Biosynthesis*
  • Protein Stability
  • Seedlings / genetics
  • Seedlings / growth & development


  • AT4G17840 protein, Arabidopsis
  • Arabidopsis Proteins
  • Enzymes
  • Intracellular Signaling Peptides and Proteins
  • magnesium dechelatase
  • Chlorophyll
  • AT2G35260 protein, Arabidopsis
  • Cysteine Endopeptidases