The RxLR motif of the Phytophthora infestans effector AVR3a is cleaved before secretion ($)

RxLR effectors are proteins secreted from pathogens that enter the cells of the host and support the effectiveness of the pathogen in various ways. Their name refers to the sequence RxLR (Arg-Xxx-Leu-Arg). Previously, this sequence has been thought to be involved the effector’s entry into the host cell.  Wawra et al. used mass spectrometry and other approaches to examine the AVR3a effector secreted from cultured Phytophthora infestans. Their data show that the effector is cleaved at the RxLR site, and the resulting protein probably acetylated at the new N-terminus. This processing is similar to the that which occurs at the PEXEL (plasmodium export element) site of effectors of the Plasmodium pathogen that causes malaria. These new data argue that the RxLR sequence is processed within the pathogen cell and therefore not  directly involved in uptake by the host cell.  Plant Cell 10.​1105/​tpc.​16.​00552