A biologically active lectin of enteroaggregative Escherichia coli.
The pathogenesis of enteroaggregative Escherichia coli, a major contributor to paediatric diarrhoea, is still not clearly understood. A complex carbohydrate specific lectin was identified from the culture supernatant of an enteroaggregative E. coli strain. The lectin was purified to 660-fold by a combination of sequential saturated ammonium sulphate precipitation and gel filtration chromatography in the FPLC system. The homogeneity of the purified lectin was established by analytical isoelectrofocusing [pI 6.75]. Hemagglutination of rabbit erythrocytes by the purified lectin was best inhibited by fetuin. The N-terminal sequence of the 41.7 kDa subunit showed homology to the outermembrane porins and the 23.4 kDa subunit showed homology to a hypothetical protein of Yersinia pestis and secreted Hcp protein. This protein could induce extensive morphological changes in HEp-2 cells and significant amount of fluid accumulation in rabbit ileal loop. GM1 showed maximum binding to the lectin among all other gangliosides. This purified protein showed cross-reactivity to the binding subunit of cholera toxin in western immunoblot. The presence of this toxin in some of the clinical isolates of enteroaggregative E. coli was also observed. The structural and functional characteristics of the toxin revealed that it is a novel virulence determinant of aggregative E. coli.
Basu
Sulagna
S
Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh 160-012, India. supabasu@yahoo.co.in
Ghosh
Sujata
S
Ganguly
N K
NK
Majumdar
S
S
D000818:Animals; D002460:Cell Line; D003968:Diarrhea, Infantile / Q000382:microbiology; D004926:Escherichia coli / Q000737:chemistry* / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000633:toxicity; D006801:Humans; D007231:Infant, Newborn; D037102:Lectins / Q000737:chemistry* / Q000302:isolation & purification* / Q000633:toxicity; D011817:Rabbits; D037521:Virulence Factors / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity
D029968:Escherichia coli Proteins; D037102:Lectins; D037521:Virulence Factors