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Molecular and Cellular Biology, September 2004, p. 7331-7344, Vol. 24, No. 17
0270-7306/04/$08.00+0     DOI: 10.1128/MCB.24.17.7331-7344.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Modulation of the Leishmania donovani Peroxin 5 Quaternary Structure by Peroxisomal Targeting Signal 1 Ligands

Kleber P. Madrid,1 Gregory De Crescenzo,2 Shengwu Wang,1 and Armando Jardim1*

Institute of Parasitology, McGill University, Ste Anne-de-Bellevue,1 Protein-Protein Interaction Group, Sheldon Biotechnology Centre, McGill University, Montreal, Quebec, Canada2

Received 23 March 2004/ Returned for modification 28 April 2004/ Accepted 3 June 2004

The import of proteins containing the peroxisomal targeting signal 1 (PTS1) into the Leishmania glycosome is dependent on the docking of the PTS1-loaded LdPEX5 cytosolic receptor with LdPEX14 on the glycosome surface. Here we show that, in the absence of PTS1, LdPEX5 is a tetramer that is stabilized by two distinct interaction domains; the first is a coiled-coil motif encompassing residues 277 to 310, whereas the second domain is localized to residues 1 to 202. By using microcalorimetry, surface plasmon resonance, and size exclusion chromatography techniques, we show that PTS1 peptide binding to LdPEX5 tetramers promotes their dissociation into dimeric structures, which are stabilized by a coiled-coil interaction. Moreover, we demonstrated that the resulting LdPEX5-PTS1 complex is remarkably stable and exhibits extremely slow dissociation kinetics. However, binding of LdPEX14 to LdPEX5 modulates the LdPEX5-PTS1 affinity as it decreases the thermodynamic dissociation constant for this latter complex by 10-fold. These changes in the oligomeric state of LdPEX5 and in its affinity for PTS1 ligand upon LdPEX14 binding may explain how, under physiological conditions, LdPEX5 can function to deliver and unload its cargo to the protein translocation machinery on the glycosomal membrane.

* Corresponding author. Mailing address: Institute of Parasitology, McGill University, 21, 111 Lakeshore Rd., Ste. Anne-de-Bellevue, Quebec H9X 3V9, Canada. Phone: (514) 398-7727. Fax: (514) 398-7857. E-mail: armando.jardim{at}mcgill.ca.

Molecular and Cellular Biology, September 2004, p. 7331-7344, Vol. 24, No. 17
0022-538X/04/$08.00+0     DOI: 10.1128/MCB.24.17.7331-7344.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Shiozawa, K., Konarev, P. V., Neufeld, C., Wilmanns, M., Svergun, D. I. (2009). Solution Structure of Human Pex5{middle dot}Pex14{middle dot}PTS1 Protein Complexes Obtained by Small Angle X-ray Scattering. J. Biol. Chem. 284: 25334-25342 [Abstract] [Full Text]  
  • Cyr, N., Madrid, K. P., Strasser, R., Aurousseau, M., Finn, R., Ausio, J., Jardim, A. (2008). Leishmania donovani Peroxin 14 Undergoes a Marked Conformational Change following Association with Peroxin 5. J. Biol. Chem. 283: 31488-31499 [Abstract] [Full Text]  
  • Costa-Rodrigues, J., Carvalho, A. F., Fransen, M., Hambruch, E., Schliebs, W., Sa-Miranda, C., Azevedo, J. E. (2005). Pex5p, the Peroxisomal Cycling Receptor, Is a Monomeric Non-globular Protein. J. Biol. Chem. 280: 24404-24411 [Abstract] [Full Text]  


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