RRC ID 30756
Author Dolze E, Chigri F, Höwing T, Hierl G, Isono E, Vothknecht UC, Gietl C.
Title Calmodulin-like protein AtCML3 mediates dimerization of peroxisomal processing protease AtDEG15 and contributes to normal peroxisome metabolism.
Journal Plant Mol. Biol.
Abstract Matrix enzymes are imported into peroxisomes and glyoxysomes, a subclass of peroxisomes involved in lipid mobilization. Two peroxisomal targeting signals (PTS), the C-terminal PTS1 and the N-terminal PTS2, mediate the translocation of proteins into the organelle. PTS2 processing upon import is conserved in higher eukaryotes, and in watermelon the glyoxysomal processing protease (GPP) was shown to catalyse PTS2 processing. GPP and its ortholog, the peroxisomal DEG protease from Arabidopsis thaliana (AtDEG15), belong to the Deg/HtrA family of ATP-independent serine proteases with Escherichia coli DegP as their prototype. GPP existes in monomeric and dimeric forms. Their equilibrium is shifted towards the monomer upon Ca(2+)-removal and towards the dimer upon Ca(2+)-addition, which is accompanied by a change in substrate specificity from a general protease (monomer) to the specific cleavage of the PTS2 (dimer). We describe the Ca(2+)/calmodulin (CaM) mediated dimerization of AtDEG15. Dimerization is mediated by the CaM-like protein AtCML3 as shown by yeast two and three hybrid analyses. The binding of AtCML3 occurs within the first 25 N-terminal amino acids of AtDEG15, a domain containing a predicted CaM-binding motif. Biochemical analysis of AtDEG15 deletion constructs in planta support the requirement of the CaM-binding domain for PTS2 processing. Phylogenetic analyses indicate that the CaM-binding site is conserved in peroxisomal processing proteases of higher plants (dicots, monocots) but not present in orthologs of animals or cellular slime molds. Despite normal PTS2 processing activity, an atcml3 mutant exhibited reduced 2,4-DB sensitivity, a phenotype previously reported for the atdeg15 mutant, indicating similarly impaired peroxisome metabolism.
Volume 83(6)
Pages 607-24
Published 2013-12
DOI 10.1007/s11103-013-0112-6
PMID 23943091
PMC PMC3830196
MeSH Arabidopsis / genetics Arabidopsis / metabolism Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism* Arabidopsis Proteins / physiology Calmodulin / metabolism Chromosomes, Artificial, Yeast / genetics Dimerization Intracellular Calcium-Sensing Proteins / genetics Intracellular Calcium-Sensing Proteins / metabolism Intracellular Calcium-Sensing Proteins / physiology Peptide Hydrolases / metabolism Peroxisomes / metabolism* Phylogeny Recombinant Proteins Sequence Alignment Serine Endopeptidases / genetics Serine Endopeptidases / metabolism Serine Endopeptidases / physiology
IF 3.543
Times Cited 4
Arabidopsis / Cultured plant cells, genes pda00743 pda02633 pda07220