Pro-sterol carrier protein-2. Role of the N-terminal presequence in structure, function, and peroxisomal targeting

F. Schroeder, A. Frolov, O. Starodub, B. B. Atshaves, W. Russell, A. Petrescu, H. Huang, A. M. Gallegos, A. McIntosh, D. Tahotna, D. H. Russell, J. T. Billheimer, C. L. Baum, A. B. Kier

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

Although the 20-amino acid presequence present in 15-kDa pro-sterol carrier protein-2 (pro-SCP-2, the precursor of the mature 13-kDa SCP-2) alters the function of SCP-2 in lipid metabolism, the molecular basis for this effect is unresolved. The presequence dramatically altered SCP-2 structure as determined by circular dichroism, mass spectroscopy, and antibody accessibility such that pro-SCP-2 had 3-fold less α-helix, 7-fold more β-structure, 6-fold more reactive C terminus to carboxypeptidase A, 2-fold less binding of anti-SCP-2, and did not enhance sterol transfer from plasma membranes. These differences were not due to protein stability since (i) the same concentration of guanidine hydrochloride was required for 50% unfolding, and (ii) the ligand binding sites displayed the same high affinity (nanomolar K(d) values) in the order: cholesterol >> straight chain fatty acid > kinked chain fatty acid. Laser scanning confocal microscopy and double immunofluorescence demonstrated that pro-SCP-2 was more efficiently targeted to peroxisomes. Transfection of L-cells or McAR7777 hepatoma cells with cDNA encoding pro-SCP-2 resulted in 45% and 59% of SCP-2, respectively, colocalizing with the peroxisomal marker PMP70. In contrast, L-cells transfected with cDNA encoding SCP-2 exhibited 3-fold lower colocalization of SCP-2 with PMP70. In summary, the data suggest for the first time that the 20-amino acid presequence of pro-SCP-2 alters SCP-2 structure to facilitate peroxisomal targeting mediated by the C-terminal SKL peroxisomal targeting sequence.

Original languageEnglish (US)
Pages (from-to)25547-25555
Number of pages9
JournalJournal of Biological Chemistry
Volume275
Issue number33
DOIs
StatePublished - Aug 18 2000

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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