title: Subunits of the Pyruvate Dehydrogenase Cluster of Mycoplasma pneumoniae Are Surface-Displayed Proteins that Bind and Activate Human Plasminogen.
abstract: The dual role of glycolytic enzymes in cytosol-located metabolic processes and in cell surface-mediated functions with an influence on virulence is described for various micro-organisms. Cell wall-less bacteria of the class Mollicutes including the common human pathogen Mycoplasma pneumoniae possess a reduced genome limiting the repertoire of virulence factors and metabolic pathways. After the initial contact of bacteria with cells of the respiratory epithelium via a specialized complex of adhesins and release of cell-damaging factors, surface-displayed glycolytic enzymes may facilitate the further interaction between host and microbe. In this study, we described detection of the four subunits of pyruvate dehydrogenase complex (PDHA-D) among the cytosolic and membrane-associated proteins of M. pneumoniae. Subunits of PDH were cloned, expressed and purified to produce specific polyclonal guinea pig antisera. Using colony blotting, fractionation of total proteins and immunofluorescence experiments, the surface localization of PDHA-C was demonstrated. All recombinant PDH subunits are able to bind to HeLa cells and human plasminogen. These interactions can be specifically blocked by the corresponding polyclonal antisera. In addition, an influence of ionic interactions on PDHC-binding to plasminogen as well as of lysine residues on the association of PDHA-D with plasminogen was confirmed. The PDHB subunit was shown to activate plasminogen and the PDHB-plasminogen complex induces degradation of human fibrinogen. Hence, our data indicate that the surface-associated PDH subunits might play a role in the pathogenesis of M. pneumoniae infections by interaction with human plasminogen.
authors.affiliation: TU Dresden, Institute of Medical Microbiology and Hygiene, Dresden, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Gründel
authors.affiliation: TU Dresden, Institute of Medical Microbiology and Hygiene, Dresden, Germany.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Friedrich
authors.affiliation: TU Dresden, Institute of Medical Microbiology and Hygiene, Dresden, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Pfeiffer
authors.affiliation: TU Dresden, Institute of Medical Microbiology and Hygiene, Dresden, Germany.
authors.forename: Enno
authors.initials: E
authors.lastname: Jacobs
authors.affiliation: TU Dresden, Institute of Medical Microbiology and Hygiene, Dresden, Germany.
authors.forename: Roger
authors.initials: R
authors.lastname: Dumke
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D006168:Guinea Pigs; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D009177:Mycoplasma pneumoniae / Q000378:metabolism*; D010958:Plasminogen / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology*; D021122:Protein Subunits / Q000378:metabolism*; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism*; D014774:Virulence / Q000502:physiology; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins; D021122:Protein Subunits; D011768:Pyruvate Dehydrogenase Complex; D037521:Virulence Factors; D010958:Plasminogen