Periplasmic chitooligosaccharide-binding protein requires a three-domain organization for substrate translocation.

Periplasmic solute-binding proteins (SBPs) specific for chitooligosaccharides, (GlcNAc) (n = 2, 3, 4, 5 and 6), are involved in the uptake of chitinous nutrients and the negative control of chitin signal transduction in Vibrios. Most translocation processes by SBPs across the inner membrane have been explained thus far by two-domain open/closed mechanism. Here we propose three-domain mechanism of the (GlcNAc) translocation based on experiments using a recombinant VcCBP, SBP specific for (GlcNAc) from Vibrio cholerae.