Extracellular proteins of Lactobacillus crispatus enhance activation of human plasminogen.
The abundant proteolytic plasminogen (Plg)/plasmin system is important in several physiological functions in mammals and also engaged by a number of pathogenic microbial species to increase tissue invasiveness or to obtain nutrients. This paper reports that a commensal bacterium, Lactobacillus crispatus, interacts with the Plg system. Strain ST1 of L. crispatus enhanced activation of human Plg by the tissue-type Plg activator (tPA), whereas enhancement of the urokinase-mediated Plg activation was lower. ST1 cells bound Plg, plasmin and tPA only poorly, and the Plg-binding and activation-enhancing capacities were associated with extracellular material released from the bacteria into buffer. The extracellular proteome of L. crispatus ST1 contained enolase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as major components. The enolase and the GAPDH genes of ST1 were cloned, sequenced and expressed in recombinant Escherichia coli as His(6)-fusion proteins, which bound Plg and enhanced its activation by tPA. Variable levels of secretion of enolase and GAPDH proteins as well as of the Plg activation cofactor function were detected in strains representing major taxonomic groups of the genus Lactobacillus. So far, interference with the Plg system has been addressed with pathogenic microbes. The results reported here demonstrate a novel interaction between a member of the microbiota and a major proteolytic system in humans.
Hurmalainen
Veera
V
General Microbiology, Faculty of Biosciences, PO Box 56, FIN00014 University of Helsinki, Finland.
Edelman
Sanna
S
General Microbiology, Faculty of Biosciences, PO Box 56, FIN00014 University of Helsinki, Finland.
Antikainen
Jenni
J
General Microbiology, Faculty of Biosciences, PO Box 56, FIN00014 University of Helsinki, Finland.
Baumann
Marc
M
Protein Chemistry Unit, Institute of Biomedicine/Anatomy, PO Box 63, FIN00014 University of Helsinki, Finland.
Lähteenmäki
Kaarina
K
General Microbiology, Faculty of Biosciences, PO Box 56, FIN00014 University of Helsinki, Finland.
Korhonen
Timo K
TK
General Microbiology, Faculty of Biosciences, PO Box 56, FIN00014 University of Helsinki, Finland.
D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D015153:Blotting, Western; D002417:Cattle; D002645:Chickens; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007778:Lactobacillus / Q000737:chemistry*; D008969:Molecular Sequence Data; D010751:Phosphopyruvate Hydratase / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D010958:Plasminogen / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
D001426:Bacterial Proteins; D010958:Plasminogen; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator; D010751:Phosphopyruvate Hydratase