The reducible complexity of a mitochondrial molecular machine

Proc Natl Acad Sci U S A. 2009 Sep 15;106(37):15791-5. doi: 10.1073/pnas.0908264106. Epub 2009 Aug 26.

Abstract

Molecular machines drive essential biological processes, with the component parts of these machines each contributing a partial function or structural element. Mitochondria are organelles of eukaryotic cells, and depend for their biogenesis on a set of molecular machines for protein transport. How these molecular machines evolved is a fundamental question. Mitochondria were derived from an alpha-proteobacterial endosymbiont, and we identified in alpha-proteobacteria the component parts of a mitochondrial protein transport machine. In bacteria, the components are found in the inner membrane, topologically equivalent to the mitochondrial proteins. Although the bacterial proteins function in simple assemblies, relatively little mutation would be required to convert them to function as a protein transport machine. This analysis of protein transport provides a blueprint for the evolution of cellular machinery in general.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Caulobacter crescentus / genetics
  • Caulobacter crescentus / metabolism
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mitochondrial Membrane Transport Proteins / chemistry
  • Mitochondrial Membrane Transport Proteins / genetics*
  • Mitochondrial Membrane Transport Proteins / metabolism*
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism
  • Models, Molecular
  • Protein Conformation
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Species Specificity

Substances

  • Bacterial Proteins
  • Carrier Proteins
  • Membrane Proteins
  • Mitochondrial Membrane Transport Proteins
  • Mitochondrial Proteins
  • Saccharomyces cerevisiae Proteins
  • TIM44 protein, S cerevisiae
  • TIMM44 protein, human