Enteroaggregative Escherichia coli (EAEC) are diarrhoeal pathogens that adhere to the intestinal mucosa in a thick biofilm that may mediate their persistence in the human intestine, but the mechanisms involved in the adhesion have been unclear. In November 1 Journal of Clinical Investigation, Jalaluddin Sheikh and colleagues at the University of Maryland School of Medicine, Baltimore, Maryland, USA, show that aap encodes a secreted protein that coats the bacterial surface and promotes dispersal of the bacteria on the intestinal mucosa (Journal of Clinical Investigation, 110:1329-1337, November 1, 2002).

Sheikh et al. generated a variety of recombinant E. coli and observed that EAEC aap mutants aggregated more intensely than wild-type cells and formed larger aggregates, but containing fewer individual bacteria. In addition, they showed that the aspU locus — which lies immediately upstream of aggR in EAEC 042 — encodes a secreted low molecular weight protein, named...

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