The thylakoid protease Deg1 is involved in photosystem-II assembly in Arabidopsis thaliana

Plant J. 2010 Apr;62(2):240-9. doi: 10.1111/j.1365-313X.2010.04140.x. Epub 2010 Jan 18.


DegP proteases have been shown to possess both chaperone and protease activities. The proteolytic activities of chloroplast DegP-like proteases have been well documented. However, whether chloroplast Deg proteases also have chaperone activities has remained unknown. Here we show that chloroplast Deg1 also has chaperone activities, like its Escherichia coli ortholog DegP. Transgenic plants with reduced levels of Deg1 accumulated normal levels of different subunits of the major photosynthetic protein complexes, but their levels of photosystem-II (PSII) dimers and supercomplexes were reduced. In vivo pulse-chase protein labeling experiments showed that the assembly of newly synthesized proteins into PSII dimers and supercomplexes was impaired, although the synthesis rate of chloroplast proteins was unaffected in the transgenic lines. Protein overlay assays provided direct evidence that Deg1 interacts with the PSII reaction center protein D2. These results suggest that Deg1 assists the assembly of the PSII complex, probably through interaction with the PSII reaction center D2 protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Chlorophyll / analysis
  • Gene Expression Regulation, Plant
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism
  • Photosystem II Protein Complex / metabolism*
  • Plants, Genetically Modified / enzymology
  • Plants, Genetically Modified / genetics
  • Protein Folding
  • RNA Interference
  • Serine Endopeptidases / genetics
  • Serine Endopeptidases / metabolism*
  • Thylakoids / enzymology*


  • Arabidopsis Proteins
  • Molecular Chaperones
  • Photosystem II Protein Complex
  • Chlorophyll
  • Deg1 protein, Arabidopsis
  • Serine Endopeptidases