Novel proteomic tools reveal essential roles of SRP and importance of proper membrane protein biogenesis

Mol Cell Proteomics. 2012 Feb;11(2):M111.011585. doi: 10.1074/mcp.M111.011585. Epub 2011 Oct 25.

Abstract

The signal recognition particle (SRP), which mediates cotranslational protein targeting to cellular membranes, is universally conserved and essential for bacterial and mammalian cells. However, the current understanding of the role of SRP in cell physiology and pathology is still poor, and the reasons behind its essential role in cell survival remain unclear. Here, we systematically analyzed the consequences of SRP loss in E. coli using time-resolved quantitative proteomic analyses. A series of snapshots of the steady-state and newly synthesized proteome unveiled three stages of cellular responses to SRP depletion, and demonstrated essential roles of SRP in metabolism, membrane potential, and protein and energy homeostasis in both the membrane and cytoplasm. We also identified a group of periplasmic proteins, including key molecular chaperones, whose localization was impaired by the loss of SRP; this and additional results showed that SRP is crucial for protein homeostasis in the bacterial envelope. These results reveal the extensive roles that SRP plays in bacterial physiology, emphasize the importance of proper membrane protein biogenesis, and demonstrate the ability of time-resolved quantitative proteomic analysis to provide new biological insights.

Publication types

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

MeSH terms

  • Cell Membrane Permeability
  • Cell Movement
  • Chromatography, Liquid
  • Cytoplasm / metabolism
  • Escherichia coli / growth & development
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / metabolism*
  • Membrane Potentials
  • Membrane Proteins / metabolism*
  • Organelle Biogenesis*
  • Protein Transport
  • Proteome / analysis*
  • Proteomics*
  • Ribosomes / metabolism
  • Signal Recognition Particle / genetics
  • Signal Recognition Particle / metabolism*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Subcellular Fractions

Substances

  • Escherichia coli Proteins
  • Membrane Proteins
  • Proteome
  • Signal Recognition Particle