Can Listeria monocytogenes endotoxin act as an A-B toxin?
Considering great research we did after the answer was accepted, I should add important information about the topic. The old (and accepted) answer follows in "" marks for the sake of clarity.

We found that in spite of the earlier reports, the newest ones failed to find endotoxin-like structure in the Listeria born material. Most academic discussions about the issue say there is no such thing called "listeric endotoxin", thus I gave a right answer to a "compromised" question. 

I should say that question is still brilliant because it promoted great research and should be an important source for everyone looking for information about listeric "endotoxin"


  Listeria endotoxin is not a protein. Thus, is lacks enzymatic activity
  and acts indirectly by binding to sensitive receptors on macrophages. 
  Thus, it can not cause lysis itself.
  
  Considering AB-exotoxins, A-subunit is a protein that has enzymatic
  activity (responsible for toxin action)  and subunit B has no
  enzymatic activity (protein responsible for binding to receptors).
  
  Thus, the answer to your brilliant question is NO, Listeria endotoxin
  cannot act as AB-exotoxin being nonprotein and non enzymatic
  substance.
  
  Also, don't be confused with Listeriolysin O, which is listeria's
  eXotoxin protein which is pore-creating protein.