Calmodulin-like protein AtCML3 mediates dimerization of peroxisomal processing protease AtDEG15 and contributes to norma
- PDF / 996,644 Bytes
- 18 Pages / 595.276 x 790.866 pts Page_size
- 4 Downloads / 171 Views
Calmodulin-like protein AtCML3 mediates dimerization of peroxisomal processing protease AtDEG15 and contributes to normal peroxisome metabolism Esther Dolze • Fatima Chigri • Timo Ho¨wing • Georg Hierl • Erika Isono • Ute C. Vothknecht Christine Gietl
•
Received: 18 December 2012 / Accepted: 17 July 2013 / Published online: 14 August 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com
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 Ca2?removal and towards the dimer upon Ca2?-addition, which is accompanied by a change in substrate specificity from a
Esther Dolze and Fatima Chigri contributed equally to this work.
Electronic supplementary material The online version of this article (doi:10.1007/s11103-013-0112-6) contains supplementary material, which is available to authorized users. E. Dolze T. Ho¨wing G. Hierl C. Gietl (&) Institute of Botany, Center of Life and Food Sciences Weihenstephan, TU Munich, Emil-Ramann-Str. 4, 85350 Freising, Germany e-mail: [email protected] F. Chigri U. C. Vothknecht Department of Biology, Center of Integrated Protein Science, LMU Munich, 82152 Martinsried, Germany E. Isono Department of Plant Systems Biology, Center of Life and Food Sciences Weihenstephan, TU Munich, 85350 Freising, Germany
general protease (monomer) to the specific cleavage of the PTS2 (dimer). We describe the Ca2?/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 CaMbinding 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 2,4DB sensitivity, a phenotype previously reported for the atdeg15 mutant, indicating similarly impaired peroxisome metabolism. Keywords AtDEG15, AtCML3 Ca2?/calmodulin Deg/HtrA serine protease Peroxisomal processing protease Abbreviations PTS Peroxisomal targeting signal pre-
Data Loading...
