I. Benz et Ma. Schmidt, DIFFUSE ADHERENCE OF ENTEROPATHOGENIC ESCHERICHIA-COLI STRAINS - PROCESSING OF AIDA-I, Zentralblatt fur Bakteriologie, 278(2-3), 1993, pp. 197-208
The adherence of pathogenic Escherichia coli to the mucosa of the smal
l intestine is an important step in the development of diarrhoea. To s
tudy the molecular basis of the diffuse adherence (DA) pattern of E. c
oli strains expressing the classical serotypes of enteropathogenic E.
coli (EPEC), strain 2787 (0126:H27) was investigated. By expression cl
oning, a plasmid-derived 6.0 kb DNA fragment was identified which conf
erred the DA phenotype on recipient K-12 strains. This fragment encode
d the 100 kDa adhesin involved in diffuse adherence (AIDA-I) which by
mild heat shock treatment was isolated from the surface of the wild-ty
pe and recombinant DA-positive strains. Analysis of the entire DNA fra
gment revealed two open reading frames coding for proteins of 45 kDa a
nd 132 kDa, respectively. The 132 kDa protein has been identified as t
he AIDA-I precursor protein which after cleavage of the signal sequenc
e undergoes additional C-terminal processing for maturation to AIDA-I.
Though the function of the cytoplasmic 45 kDa protein is not known, p
reliminary evidence indicates that authentic expression of the protein
is a prerequisite for the correct processing of the 132 kDa precursor
to AIDA-I. The AIDA-I precursor exhibits significant homology to the
virG (icsA) protein of Shigella flexneri which apparently plays a majo
r role in the events leading to the intercellular spread of invasive S
higella organisms.