Molecular Biology Of The Cell 6th Edition by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter

Exercise 15

Which statements are true? explain why or why not.
-The Gram-negative bacterium Yersinia pestis, the causative agent of the plague, is extremely virulent. Upon infection, Y. pestis injects a set of effector proteins into macrophages that suppresses their phagocytic behavior and also interferes with their innate immune responses. One of the effector proteins, acetylates serines and threonines on various MAP kinases, including the MAP kinase kinase kinase TAK1, which controls a key signaling step in the innate immune response pathway. To deter- mine how YopJ interferes with TAK1, you transfect human cells with active YopJ or inactive YopJ and with FLAG-tagged active TAK1 or inactive TAK1 and assay for total TAK1 and for phos- phorylated TAK1, using antibodies against the FLAG tag or against phosphorylated TAK1 (Figure Q23-1). How does YopJ block the TAK1 signaling pathway? How do you sup- pose the serine/threonine acetylase activity of YopJ might interfere with TAK1 activation?