Mitochondrial presequences can induce aggregation of unfolded proteins.
We have studied the interactions between various synthetic peptides and two model unfolded proteins, reduced alpha-lactalbumin and reduced and carboxymethylated alpha-lactalbumin. We found that mitochondrial presequences could induce aggregation of the unfolded alpha-lactalbumins but not of the native alpha-lactalbumin. The presequence-induced aggregation of unfolded alpha-lactalbumin was dependent on electrostatic interactions and on the amphiphilicity of the presequences. Since positive charge and amphiphilicity are necessary for the targeting function of mitochondrial presequences, presequence-induced aggregation may be responsible for the instability of mitochondrial precursor proteins and may need to be inhibited by binding factors in the cytosol.
Endo
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Department of Chemistry, Faculty of Science, Nagoya University, Japan.
Mitsui
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Roise
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D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D004563:Electrochemistry; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000494:pharmacology; D007700:Kinetics; D007768:Lactalbumin / Q000737:chemistry*; D046911:Macromolecular Substances; D008745:Methylation; D008928:Mitochondria / Q000737:chemistry*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000494:pharmacology; D017510:Protein Folding; D011498:Protein Precursors / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000201:enzymology
D046911:Macromolecular Substances; D010446:Peptide Fragments; D011498:Protein Precursors; D007768:Lactalbumin; D003576:Electron Transport Complex IV