Structural adaptation of the plant protease Deg1 to repair photosystem II during light exposure

• Published in: Nature structural & molecular biology Vol. 18; no. 6; pp. 728 - 731
• Main Authors: Adam, Zach, Clausen, Tim, Kley, Juliane, Schmidt, Bastian, Boyanov, Boril, Stolt-Bergner, Peggy C, Kirk, Rebecca, Ehrmann, Michael, Knopf, Ronit R, Naveh, Leah
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.06.2011; Nature Publishing Group
• Subjects: 631/337/474; 631/449/2675; 631/45/535; Acidification; Arabidopsis - enzymology; Arabidopsis - radiation effects; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - metabolism; Biochemistry; Biological Microscopy; Biomedical and Life Sciences; brief-communication; Crystal structure; Crystallography, X-Ray; Hydrogen-Ion Concentration; Life Sciences; Light; Membrane Biology; Models, Biological; Models, Molecular; Molecular biology; Photosynthesis; Photosystem II Protein Complex - metabolism; Plant biology; Proteases; Protein Conformation; Protein Multimerization; Protein Structure; Protein Structure, Quaternary; Protein Structure, Tertiary; Serine Endopeptidases - chemistry; Serine Endopeptidases - metabolism
• ISSN: 1545-9993; 1545-9985
• DOI: 10.1038/nsmb.2055

Deg1 is a chloroplastic protease involved in maintaining the photosynthetic machinery. Structural and biochemical analyses reveal that the inactive Deg1 monomer is transformed into the proteolytically active hexamer at acidic pH. The change in pH is sensed by His244, which upon protonation, repositions a specific helix to trigger oligomerization. This system ensures selective activation of Deg1 during daylight, when acidification of the thylakoid lumen occurs and photosynthetic proteins are damaged.