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Characterization of an iron-regulated alpha-enolase of Bacteroides fragilis

Robert Sijbrandi1, Tanneke Den Blaauwen, Jeremy R H Tame

  • 1Department of Molecular Microbiology, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.

Microbes and Infection
|February 18, 2005
PubMed

Insights

Bacteroides fragilis alpha-enolase (P46) is identified and characterized. Its location shifts to the inner membrane under iron restriction, but it

Area of Science:

  • Microbiology
  • Molecular Biology
  • Bacterial Pathogenesis

Background:

  • Bacteroides fragilis is a human gut commensal and opportunistic pathogen.
  • Virulence factors in B. fragilis are often upregulated during iron or heme starvation.
  • Alpha-enolases in other bacteria and eukaryotes can be cell surface proteins involved in plasminogen binding.

Purpose of the Study:

  • To identify, clone, and characterize the alpha-enolase P46 from Bacteroides fragilis.
  • To investigate the cellular localization of P46, particularly under iron-restricted conditions.
  • To determine if P46 is involved in plasminogen binding in B. fragilis.

Main Methods:

  • Protein identification via mass spectrometry.
  • Gene cloning and molecular characterization.
  • Cellular fractionation and protein localization studies.
  • Plasminogen binding assays.

Main Results:

  • A 46 kDa protein (P46) upregulated under iron-depleted conditions was identified as alpha-enolase.
  • P46 is primarily cytoplasmic but associates with the inner membrane (IM) under iron restriction.
  • Plasminogen binding to B. fragilis cells was observed but was not dependent on P46.
  • A distinct 60 kDa protein was identified as a potential plasminogen-binding protein.

Conclusions:

  • Bacteroides fragilis alpha-enolase (P46) exhibits altered localization under iron-restricted conditions.
  • P46 is not the primary plasminogen-binding protein in B. fragilis.
  • Further investigation is needed to identify the actual plasminogen-binding protein in B. fragilis.

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