Family of Deg/Htr proteases in the cyanobacterium Synechocystis sp. PCC6803: investigations toward their expression and function

摘要

The members of the Deg/Htr family of serine endopeptidases are present in all living organisms investigated so far. While Prokaryota like Escherichia coli or cyanobacteria contain 3 members of the Deg/Htr family, in Eukaryota the number of Deg/Htr isomers varies between 2 (e.g. in human) and 13 (e.g. in Arabidopsis thaliana). It was shown recently that one member of the Deg/Htr family from Arabidopsis, called DegP2 performs the primary cleavage of the photodamaged D1 protein from the photosystem II(PSII) reaction center (Hausuhl et al., 2001). The degradation of the D1 protein in higher plants and cyanobacteria occurs in at least two steps (reviewed in Aro et al., 1993). The primary cleavage of this protein takes place at the stromal loop connecting transmembrane alpha-helices D and E generating two proteolytic fragments. The secondary proteolysis involves a further degradation of these intermediates (Lindahl et al., 2000).