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Functional identification of the SecB homologue in Methanococcus jannaschii and direct interaction of SecB with

Sung Chul Ha1, Tae-Hee Lee, Sun-Shin Cha

  • 1Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Republic of Korea.

Biochemical and Biophysical Research Communications
|February 27, 2004
PubMed

Insights

Researchers identified Mj0357 protein from Methanococcus jannaschii as a functional SecB homologue. This archaeal protein shares chaperone-like activity and interacts with E. coli trigger factor, suggesting conserved translocation pathways.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Archaea Biology

Background:

  • SecB is a crucial chaperone protein in E. coli involved in protein translocation.
  • Mj0357 protein from Methanococcus jannaschii shares sequence similarity with E. coli SecB.
  • Understanding archaeal protein folding and translocation mechanisms is vital.

Purpose of the Study:

  • To identify and characterize a functional homologue of SecB in Methanococcus jannaschii.
  • To investigate the chaperone-like activities and structural properties of Mj0357 protein.
  • To explore the interaction between Mj0357 protein and E. coli trigger factor (TF).

Main Methods:

  • Biochemical and biophysical examinations were employed.
  • Structural analysis revealed Mj0357 protein is primarily beta-strand composed and forms a homotetramer.
  • In vitro assays assessed chaperone activity, including suppression of thermal aggregation and binding to partially folded proteins.

Main Results:

  • Mj0357 protein demonstrated significant chaperone-like activity, similar to E. coli SecB.
  • The protein binds peptide ligands, inducing conformational changes that expose hydrophobic patches.
  • E. coli trigger factor was shown to bind both E. coli SecB and Mj0357 protein, indicating a direct interaction.

Conclusions:

  • Mj0357 protein is a functional homologue of SecB in Methanococcus jannaschii.
  • The observed properties suggest a conserved protein translocation pathway between bacteria and archaea.
  • The interaction with trigger factor implies a conserved mechanism within the SecB-dependent pathway.

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