YERSINIA-ENTEROCOLITICA INDUCES APOPTOSIS IN MACROPHAGES BY A PROCESSREQUIRING FUNCTIONAL TYPE-III SECRETION AND TRANSLOCATION MECHANISMS AND INVOLVING YOPP, PRESUMABLY ACTING AS AN EFFECTOR PROTEIN

Yersiniae, causative agents of plague and gastrointestinal diseases, s ecrete and translocate Yop effector proteins into the cytosol of macro phages, leading to disruption of host defense mechanisms, It is shown in this report that Yersinia enterocolitica induces apoptosis in macro phages and that this effect depends on YopP, Functional secretion and translocation mechanisms are required for YopP to act, strongly sugges ting that this protein exerts its effect intracellularly, after transl ocation into the macrophages, YopP shows a high level of sequence simi larity with AvrRxv, an avirulence protein from Xanthomonas campestris, a plant pathogen that induces programmed cell death in plant cells, T his indicates possible similarities between the strategies used by pat hogenic bacteria to elicit programmed cell death in both plant and ani mal hosts.