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Mutations in the passenger polypeptide can affect its partitioning between mitochondria and cytoplasm: mutations can

Viktoriya Pastukh1, Inna N Shokolenko, Glenn L Wilson

  • 1Department of Cell Biology and Neuroscience, University of South Alabama, 307 University Blvd., MSB1201, Mobile, AL 36688, USA.

Molecular Biology Reports
|March 27, 2007
PubMed

Insights

Mitochondrial import efficiency is influenced by both matrix targeting sequences (MTSs) and variations within the DsRed protein itself. Amino acid changes in DsRed significantly impact its ability to reach mitochondria.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Protein Trafficking

Background:

  • Mitochondrial targeting sequences (MTSs) direct proteins to mitochondria.
  • DsRed fluorescent protein variants, mCherry and DsRed Express (DRE), are used to study protein import.
  • Understanding factors affecting mitochondrial import is crucial for various biological studies.

Purpose of the Study:

  • To investigate how different MTSs and amino acid substitutions in DsRed affect its mitochondrial and cytoplasmic partitioning.
  • To determine the roles of both the MTS and the passenger polypeptide in mitochondrial import efficiency.

Main Methods:

  • Fusion of mCherry and DRE variants to six different MTSs.
  • Analysis of mitochondrial vs. cytoplasmic localization of the fusion proteins.
  • Construction and evaluation of chimeric proteins between mCherry and DRE.

Main Results:

  • MTSs from superoxide dismutase and DNA polymerase gamma failed to target mCherry to mitochondria, but not DRE.
  • Differences in mitochondrial partitioning were attributed to variations in the primary amino acid sequence of the passenger polypeptide (mCherry vs. DRE).
  • Impaired mitochondrial import correlated with the number of mCherry-specific mutations, regardless of their location.

Conclusions:

  • Both the MTS and the passenger polypeptide's amino acid sequence significantly influence mitochondrial import efficiency.
  • The study provides a rationale for the diversity observed in natural MTS sequences.
  • These findings have implications for protein engineering and understanding mitochondrial protein targeting.

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