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Control of SecA and SecM translation by protein secretion

Hitoshi Nakatogawa1, Akiko Murakami, Koreaki Ito

  • 1Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan.

Current Opinion in Microbiology
|April 6, 2004
PubMed

Insights

SecM (secretion monitor) protein arrest during translation regulates SecA (secretion ATPase) expression in E. coli. This essential mechanism ensures cell viability and controls SecA function.

Area of Science:

  • Bacterial protein secretion
  • Molecular mechanisms of gene regulation
  • Cellular stress responses

Background:

  • SecA is the essential ATPase motor for protein translocation across the E. coli inner membrane.
  • SecA expression is tightly regulated in response to cellular secretion demands.
  • SecM acts as a negative regulator of SecA translation.

Purpose of the Study:

  • To elucidate the mechanism by which SecM regulates SecA expression.
  • To identify the functional role of SecM's translational arrest.
  • To understand the contribution of SecM to E. coli viability and SecA functionality.

Main Methods:

  • Analysis of secM-secA mRNA structure and translation.
  • Site-directed mutagenesis of the SecM arrest sequence.
  • Assessment of E. coli viability and SecA expression under different secretion conditions.

Main Results:

  • SecM translation arrests at Pro166, mediated by an arrest sequence interacting with the ribosomal exit tunnel.
  • Ribosome stalling exposes the Shine-Dalgarno sequence for SecA translation.
  • SecM elongation arrest is essential for E. coli viability and regulates SecA expression.
  • Elongation-arresting SecM may enhance SecA functionality by localizing mRNA near the membrane.

Conclusions:

  • SecM-mediated translational arrest is a critical regulatory mechanism for SecA biogenesis in E. coli.
  • This process links protein secretion status to the expression and function of the core translocation machinery.
  • The findings highlight the intricate interplay between translation, mRNA structure, and protein secretion.

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