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Elongation factor Tu and E1 beta subunit of pyruvate dehydrogenase complex act as fibronectin binding proteins in

Shatha F Dallo1, T R Kannan, Mark W Blaylock

  • 1Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, TX 78229, USA.

Molecular Microbiology
|November 8, 2002
PubMed

Insights

Mycoplasma pneumoniae uses elongation factor Tu (EF-Tu) and pyruvate dehydrogenase E1 beta subunit (PDH-B) on its surface to bind fibronectin (Fn), aiding infection. These surface proteins are key to bacterial adherence to the extracellular matrix.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Pathogenic bacteria interactions with the extracellular matrix (ECM) are crucial for infection establishment.
  • Mycoplasma pneumoniae is a significant human pathogen.

Purpose of the Study:

  • To identify and characterize surface proteins of Mycoplasma pneumoniae involved in fibronectin (Fn) binding.
  • To investigate the role of these Fn-binding proteins (FnBPs) in bacterial adherence.

Main Methods:

  • Purification of 45 kDa and 30 kDa proteins from M. pneumoniae using Fn-affinity chromatography.
  • Identification of proteins as elongation factor Tu (EF-Tu) and pyruvate dehydrogenase E1 beta subunit (PDH-B) via amino acid sequencing.
  • Gene cloning, protein overexpression in E. coli, and purification of recombinant proteins (rEF-Tu, rNPDH-B).
  • Binding assays (ligand immunoblot, ELISA), immunogold electron microscopy, and radioimmunoprecipitation to confirm surface localization and Fn binding.
  • Inhibition assays using antisera against recombinant proteins to assess the role in adherence.

Main Results:

  • Two M. pneumoniae surface proteins, EF-Tu (45 kDa) and PDH-B (30 kDa), were identified as fibronectin-binding proteins (FnBPs).
  • Recombinant EF-Tu and PDH-B proteins demonstrated direct binding to fibronectin.
  • Immunological and microscopy techniques confirmed the surface localization of EF-Tu and PDH-B.
  • Antisera against EF-Tu and PDH-B significantly inhibited M. pneumoniae adherence to fibronectin in a dose-dependent manner.

Conclusions:

  • Mycoplasma pneumoniae EF-Tu and PDH-B function as surface proteins involved in fibronectin binding.
  • These surface proteins contribute to the adherence of M. pneumoniae to the extracellular matrix, playing a role in infection.
  • Beyond their known cytoplasmic roles, EF-Tu and PDH-B exhibit moonlighting functions as surface translocated proteins conferring biological advantages.

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