Chloroplast Deg proteases

For some chloroplast proteases ATP binding and hydrolysis is not necessary for their catalytic activity, most probably because even strongly unfolded substrates may penetrate their catalytic chamber. Deg1, 2, 5 and 8 are the best known of Arabidopsis thaliana ATP- independent chloroplast proteases,...

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Bibliographic Details
Published inPostępy biochemii Vol. 57; no. 1; p. 109
Main Authors Grabsztunowicz, Magda, Luciński, Robert, Baranek, Małgorzata, Sikora, Bogna, Jackowski, Grzegorz
Format Journal Article
LanguagePolish
Published Poland 2011
Subjects
Arabidopsis Proteins - chemistry
Arabidopsis Proteins - metabolism
Chloroplasts - enzymology
Peptide Hydrolases - metabolism
Serine Endopeptidases - chemistry
Serine Endopeptidases - metabolism
Substrate Specificity
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Summary:For some chloroplast proteases ATP binding and hydrolysis is not necessary for their catalytic activity, most probably because even strongly unfolded substrates may penetrate their catalytic chamber. Deg1, 2, 5 and 8 are the best known of Arabidopsis thaliana ATP- independent chloroplast proteases, encoded by orthologues of genes coding for DegP, DegQ and DegS proteases of Escherichia coli. Current awareness in the area of structure and functions of chloroplast Degs is much more limited vs the one about their bacterial counterparts. Deg5 and Deg8 form a catalytic heterododecamer which is loosely attached to luminal side of thylakoid membrane. The complex catalyses--supported by Deg1 and one of FtsH proteases--the degradation of PsbA damaged due to plant exposition to elevated irradiance and thus these protease are of key importance for the plants' sensitivity to photoinhibition. Deg2 role in the disposal of damaged PsbA has not been elucidated. Recombinant Deg1 may degrade PsbO and plastocyanin in vitro but it is not clear whether this reaction is performed in vivo as well.
ISSN:0032-5422