Two novel mitochondrial and chloroplastic targeting-peptide-degrading peptidasomes in A. thaliana, AtPreP1 and AtPreP2.
Two novel metalloendopeptidases in Arabidopsis thaliana, AtPreP1 and AtPreP2, are responsible for the degradation of targeting peptides in mitochondria and chloroplasts. Both AtPreP1 and AtPreP2 contain ambiguous targeting peptides and are dually targeted to both organelles. The proteases also have the capacity to degrade unstructured peptides of up to 65 amino acid residues, but not small proteins. The catalysis occurs in a huge catalytic chamber revealed by the crystal structure of AtPreP1 at 2.1 A. The enzymes show a preference for basic and small uncharged amino acids or serines at the cleavage sites. Despite similarities in cleavage specificities, cleavage-site recognition differs for both proteases and is context- and structure-dependent. The AtPreP1 and AtPreP2 genes are differentially expressed in Arabidopsis.
Glaser
Elzbieta
E
Department for Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden. e_glaser@dbb.su.se
Nilsson
Stefan
S
Bhushan
Shashi
S
D000818:Animals; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000201:enzymology*; D006801:Humans; D008928:Mitochondria / Q000201:enzymology*; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity
D029681:Arabidopsis Proteins; D010447:Peptide Hydrolases; C501884:PrePI protein, Arabidopsis; C501885:PrePII protein, Arabidopsis