Deletion of the gene family of small chlorophyll-binding proteins (ScpABCDE) offsets C/N homeostasis in Synechocystis PCC 6803

Biochim Biophys Acta. 2016 Apr;1857(4):396-407. doi: 10.1016/j.bbabio.2015.11.011. Epub 2015 Dec 2.


In the family of chlorophyll binding proteins, single helix small CAB-like proteins (SCPs) are found in all organisms performing oxygenic photosynthesis. Here, we investigated the function of these stress-inducible proteins in the cyanobacterium Synechocystis sp. PCC 6803. We compared physiological, proteome and transcriptome traits of a Photosystem I (PSI) deletion strain, which constitutively induces SCPs, and a PSI-less/ScpABCDE(-) without SCPs. The SCP mutant cells were larger in size, showed irregular thylakoid structure and differed in cell-surface morphology. Deletion of scp genes strongly affected the carbon (C) and nitrogen (N) balance, resulting in accumulation of carbohydrates and a decrease in N-rich compounds (proteins and chlorophyll). Data from transcriptomic and metabolomic experiments revealed a role of SCPs in the control of chlorophyll biosynthesis. Additionally, SCPs diminished formation of reactive oxygen species, thereby preventing damage within Photosystem II. We conclude that the lack of SCP-function to remove free chlorophyll under stress conditions has a large impact on the metabolism of the entire cell.

Keywords: C/N metabolism; Cyanobacterium (Synechocystis sp. strain PCC 6803); High light protection; Pleiotropic effects; Small chlorophyll-proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon / metabolism*
  • Chlorophyll Binding Proteins / genetics
  • Chlorophyll Binding Proteins / physiology*
  • Gene Deletion
  • Gene Expression Profiling
  • Homeostasis
  • Metabolomics
  • Nitrogen / metabolism*
  • Reactive Oxygen Species / metabolism
  • Synechocystis / metabolism*


  • Chlorophyll Binding Proteins
  • Reactive Oxygen Species
  • Carbon
  • Nitrogen