The thylakoid protease Deg2 is involved in stress-related degradation of the photosystem II light-harvesting protein Lhcb6 in Arabidopsis thaliana

New Phytol. 2011 Oct;192(1):74-86. doi: 10.1111/j.1469-8137.2011.03782.x. Epub 2011 Jun 13.


• The thylakoid protease Deg2 is a serine-type protease peripherally attached to the stromal side of the thylakoid membrane. Given the lack of knowledge concerning its function, two T-DNA insertion lines devoid of Deg2 were prepared to study the functional importance of this protease in Arabidopsis thaliana. • The phenotypic appearance of deg2 mutants was studied using a combination of stereo and transmission electron microscopy, and short-stress-mediated degradation of apoproteins of minor light-harvesting antennae of photosystem II (PSII) was analysed by immunoblotting in the mutants in comparison with wild-type plants. • Deg2 repression produced a phenotype in which reduced leaf area and modified chloroplast ultrastructure of older leaves were the most prominent features. In contrast to the wild type, the chloroplasts of second-whorl leaves of 4-wk-old deg2 mutants did not display features typical of the early senescence phase, such as undulation of the chloroplast envelope and thylakoids. The ability to degrade the photosystem II light-harvesting protein Lhcb6 apoprotein in response to brief high-salt, wounding, high-temperature and high-irradiance stress was demonstrated to be impaired in deg2 mutants. • Our results suggest that Deg2 is required for normal plant development, including the chloroplast life cycle, and has an important function in the degradation of Lhcb6 in response to short-duration stresses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoproteins / metabolism
  • Aprotinin / pharmacology
  • Arabidopsis / drug effects
  • Arabidopsis / enzymology*
  • Arabidopsis / ultrastructure
  • Arabidopsis Proteins / metabolism*
  • Chlorophyll Binding Proteins / metabolism*
  • DNA, Bacterial / genetics
  • Immunoblotting
  • Light-Harvesting Protein Complexes / metabolism*
  • Mutagenesis, Insertional / drug effects
  • Mutagenesis, Insertional / genetics
  • Phenotype
  • Photosystem II Protein Complex / metabolism*
  • Plant Leaves / drug effects
  • Plant Leaves / metabolism
  • Plant Leaves / ultrastructure
  • Proteolysis / drug effects
  • Serine Endopeptidases / metabolism*
  • Stress, Physiological* / drug effects
  • Thylakoids / drug effects
  • Thylakoids / enzymology*
  • Thylakoids / ultrastructure


  • Apoproteins
  • Arabidopsis Proteins
  • Chlorophyll Binding Proteins
  • DNA, Bacterial
  • Lhcb6 protein, Arabidopsis
  • Light-Harvesting Protein Complexes
  • Photosystem II Protein Complex
  • T-DNA
  • Aprotinin
  • Deg2 protein, Arabidopsis
  • Serine Endopeptidases