Chitin-binding is associated with the N-terminal Cys-rich domain of Jessie3.

<p>Left panel: Coomassie blue stained SDS-PAGE shows an MBP-fusion-protein containing the CBD of Jessie3, which was purified with an amylose resin. A lower mol wt band is likely MBP alone, as only the MBP-Jessie3 CBD fusion-protein binds to chitin (right lane). Left center panel: A Coomassie-stained MBP-fusion-protein containing the C-terminal unique domain of Jessie3, which was purified with the amylose resin (left lane), fails to bind to chitin (right lane). Right center panel: A Western blot with polyclonal rabbit antibodies to Jessie3 shows that an MBP-fusion-protein containing full-length Jessie3 self-aggregates, so that it is difficult to purify on the amylose resin (left lane). However, the MBP-full-length Jessie3 fusion-protein binds to chitin (right lane). Right panel: Polyclonal rabbit anti-Jessie3 antibodies bind weakly to trophozoites of Ei (left lane) but bind strongly to an ∼60-kDa protein in encysting Ei (the expected size of Jessie3) (right lane). Lower molecular weight bands may reflect a cleavage product between the N-terminal CBD and the C-terminal unique domain, as we have previously shown that Jacob lectins of encysting Ei are often cleaved between CBDs <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1000498#ppat.1000498-Frisardi1" target="_blank">[9]</a>. There was no binding of a control non-immune sera to trophozoite or cyst proteins (not shown).