Disruption of Signaling by Yersinia Effector YopJ, a Ubiquitin-Like Protein Protease

Abstract

Homologs of the Yersinia virulence effector YopJ are found in both plant and animal bacterial pathogens, as well as plant symbionts. These YopJ family members were shown to act as cysteine proteases. The catalytic triad of the protease was required for inhibition of the mitogen-activated protein kinase (MAPK) and nuclear factor kappaB (NF-kappaB) signaling in animal cells and for induction of localized cell death in plants. The substrates for YopJ were shown to be highly conserved ubiquitin-like molecules, which are covalently added to numerous regulatory proteins. YopJ family members exert their pathogenic effect on cells by disrupting this posttranslational modification.

Identification of a host 14-3-3 protein that interacts with Xanthomonas effector AvrRxv

“…AvrRxv is a member of a family of pathogen effectors [6][7][8], that are translocated into host cells by the Type III secretion system (TTSS). AvrRxv exerts its effect intracellularly [9].…”

“…In addition to AvrRxv, there are three other AvrRxv family members present in Xcv. These are AvrBsT, XopJ and AvrXv4 [6,10,11], all of which are translocated to the host cell [8,12,13]. Genes with high levels of sequence similarity are also present in other plant pathogens [14][15][16][17][18], and in the plant symbiont Rhizobium [19].…”

“…Previously, it was hypothesized that family members were similar to cysteine proteases [8,26,27]. Apparently, the catalytic triad that is conserved in all members of the family, may have acetyltransferase rather than protease activity [25].…”

“…Apparently, the catalytic triad that is conserved in all members of the family, may have acetyltransferase rather than protease activity [25]. Mutation of any amino acid in the triad results in loss of function in YopJ, AvrBsT, AvrRxv and AvrXv4 [8,13,23]. It is not clear how to interpret analyses indicating that YopJ and AvrXv4 disrupt SUMO post-translation modifications in host cells [8,13], except possibly by affecting expression levels [25].…”

“…Mutation of any amino acid in the triad results in loss of function in YopJ, AvrBsT, AvrRxv and AvrXv4 [8,13,23]. It is not clear how to interpret analyses indicating that YopJ and AvrXv4 disrupt SUMO post-translation modifications in host cells [8,13], except possibly by affecting expression levels [25]. In mammalian hosts, YopJ exerts its effect on several known signal transduction pathways, thereby preventing an immune response [28][29][30][31][32][33].…”