title: Galactose-specific fimbrial adhesin of enteroaggregative Escherichia coli: a possible aggregative factor.
abstract: A galactose-specific adhesin was isolated from the fimbriae of an enteroaggregative Escherichia coli (EAEC) strain. The adhesin was found to be a high molecular weight aggregate of the 18-kDa monomer. The dimeric (36 kDa) and tetrameric (76 kDa) forms appeared in sodium dodecyl sulphate polyacrylamide gel electrophoresis when a higher concentration of the adhesin was used. The IgGAD (IgG against adhesin) obtained from the immune sera raised in rabbits against purified adhesin could detect all three forms of the adhesin even from the crude fimbrial preparation. The IgGAD failed to recognize the adhesin in the presence of galactose, thereby suggesting the antibody-binding site and the sugar-binding site on the adhesin might be same or overlapping. Furthermore, the IgGAD could localize the adhesin exclusively on the fimbriae as observed in immunogold electron microscopy. The aggregative adherence of the bacteria to HEp-2 cells was reduced to 70% in the presence of the IgGAD. A glycoprotein (34 kDa) present in the membrane fraction of HEp-2 cells interacted with the purified adhesin in a galactose-specific manner. The IgGAD could recognize the adhesin from the crude fimbrial preparation of 9 out of 10 clinical isolates of EAEC strains but failed to identify any protein from the crude fimbrial preparation of Salmonella typhimurium (fim +ve as well as fim -ve strain), Vibrio cholerae (WO7) or Escherichia coli DH5alpha.
authors.affiliation: Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh 160 012, India.
authors.forename: Vandana
authors.initials: V
authors.lastname: Grover
authors.forename: Sujata
authors.initials: S
authors.lastname: Ghosh
authors.forename: Anuradha
authors.initials: A
authors.lastname: Chakraborti
authors.forename: Siddhartha
authors.initials: S
authors.lastname: Majumdar
authors.forename: Nirmal Kumar
authors.initials: NK
authors.lastname: Ganguly
mesh_terms: D018829:Adhesins, Bacterial / Q000302:isolation & purification* / Q000378:metabolism*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000378:metabolism; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D004847:Epithelial Cells / Q000382:microbiology; D004926:Escherichia coli / Q000737:chemistry* / Q000502:physiology; D029968:Escherichia coli Proteins / Q000302:isolation & purification / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000737:chemistry* / Q000502:physiology; D005690:Galactose / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000097:blood / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D023421:Models, Animal; D008970:Molecular Weight; D046912:Multiprotein Complexes; D011485:Protein Binding; D011817:Rabbits; D012486:Salmonella typhimurium / Q000737:chemistry; D014734:Vibrio cholerae / Q000737:chemistry
chemical_list: D018829:Adhesins, Bacterial; D000907:Antibodies, Bacterial; D029968:Escherichia coli Proteins; D007074:Immunoglobulin G; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D005690:Galactose