In vitro recognition of a 190 kda putative attachment receptor from the cuticle of Meloidogyne javanica by Pasteuria penetrans spore extract
Studies were undertaken to develop an improved understanding of the mechanism by which spores of Pasteuria penetrans bind to the cuticle of susceptible nematode hosts. A polyclonal antibody recognized an antigenic ladder at Mr similar to 41 kDa when Meloidogyne javanica cuticle extracts were electrophoresed in the presence of SDS and blotted on to a nitrocellulose membrane. Digestion of the cuticle extracts prior to electrophoresis with Proteinase K and lipase showed the antigenic ladder to be a protein. Attempts to block the antigenic ladder with N-acetylglucosamine in the form of chitobiose did not prevent the binding of the antibody and the chitobiose could not be detected binding to the antigenic ladder using the lectin wheat germ agglutinin (WGA). Blots probed with Pasteuria spore extract and visualized with a polyclonal antibody to the spore showed that the spore extract did not bind to the antigenic ladder but did bind to a protein with Mr similar to 190 kDa and a much weaker band at similar to 45 kDa. An antibody to the lectin WGA (anti-WGA) recognized the similar to 190 kDa polypeptide but this was not blocked by chitobiose. Concanavalin A also recognized the similar to 190 kDa protein and the presence of inhibitory sugars prohibited Con A from binding, showing the protein to be glycosylated. It is conjectured that the similar to 190 kDa glycoprotein present in the cuticle extract is a binding receptor involved by the attachment of Pasteuria spores to the nemantode cuticle.