FIG. 1.

Model for repeat-mediated variation in Cha adhesive activity. The Cha protein is cartooned with the β-domain membrane anchor in green and the head domain, which contains the adhesin activity, in blue. The stalk region of Cha is shown in yellow and red, with red corresponding to the region encoded by the repeated sequence. The outer membrane, OM, periplasm, P, and extracellular environment, E, are indicated. (A) Cha variants containing a small number of repeats have a short stalk region which does not allow head-head interactions. (B) Cha variants containing a large number of repeats have stalks of sufficient length and flexibility to allow the head regions to bind each other.