Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (EC 1.2.1.12) is an anchorless, 
multifunctional protein displayed on the surface of several fungi and 
Gram-positive pathogens, which contributes to their adhesion and virulence. To 
date a role for extracellular GAPDH in the pathogenesis of Gram-negative 
bacteria has not been described. The aim of this study was to analyze the 
extracellular localization of GAPDH in enterohemorrhagic (EHEC) and 
enteropathogenic (EPEC) Escherichia coli strains and to examine its interaction 
with host components that could be related to the infection mechanism. 
Recombinant E. coli GAPDH was purified and polyclonal antibodies were obtained. 
Western blotting and immunoelectron microscopy showed that GAPDH is located on 
the bacterial surface and released to the culture medium of EHEC and EPEC 
strains. GAPDH export in these Gram-negative pathogens depends on the external 
medium, is not mediated by vesicles and leads to an extracellular active enzyme. 
Non-pathogenic E. coli strains do not secrete GAPDH. Two-dimensional 
electrophoresis analysis showed that in E. coli GAPDH is present at least in two 
major forms with different isoelectric points. Of these forms, the more basic is 
secreted. Purified GAPDH was found to bind human plasminogen and fibrinogen in 
Far-Western blot and ELISA-based assays. In addition, GAPDH remained associated 
with colonic Caco-2 epithelial cells after adhesion of EHEC or EPEC. These 
observations indicate that exported GAPDH may act as a virulence factor which 
could contribute to EHEC and EPEC pathogenesis. This is the first description of 
an extracellular localization for this enzyme, with a function other than its 
glycolytic role in Gram-negative pathogens.