Identification and characterization of VopT, a novel ADP-ribosyltransferase effector protein secreted via the Vibrio parahaemolyticus type III secretion system 2

Abstract

SummaryVibrio parahaemolyticus strain RIMD2210633 has two sets of genes encoding two separate type III secretion systems (T3SSs), called T3SS1 and T3SS2. T3SS2 has a role in enterotoxicity and is present only in Kanagawa phenomenon-positive strains, which are pathogenic to humans. Accordingly, T3SS2 is considered to be closely related to V. parahaemolyticus human pathogenicity. Despite this, the biological actions of T3SS2 and the identity of the effector protein(s) secreted by this system have not been well understood. Here we report that T3SS2 induces a cytotoxic effect in Caco-2 and HCT-8 cells. Moreover, it was revealed that VPA1327 (vopT), a gene encoded within the proximity of T3SS2, is partly responsible for this cytotoxic effect. The VopT shows approximately 45% and 44% identity with the ADPribosyltransferase (ADPRT) domain of ExoT and ExoS, respectively, which are two T3SS-secreted effectors of Pseudomonas aeruginosa. T3SS2 was found to be necessary not only for the secretion, but also for the translocation of the VopT into host cells. We also demonstrate that VopT ADP-ribosylates Ras, a member of the low-molecular-weight G (LMWG) proteins both in vivo and in vitro. These results indicate that VopT is a novel ADPRT effector secreted via V. parahaemolyticus T3SS.

Regulation of type III secretion system 1 gene expression inVibrio parahaemolyticusis dependent on interactions between ExsA, ExsC, and ExsD

“…29,30,[32][33][34][35][36] For example, VopS (Vp1686) is secreted 29 and translocated 33,37 into host cells by T3SS1 where it inhibits Rho GTPase 37 and NFkappaB activity, 30 leading to depolymerization of actin structure 37 and apoptosis, 30 respectively. Further studies show that VopS (Vp1686) inhibits Rho GTPase activity by modifying a conserved residue with AMP.…”

Diarrhea induced by infection of <I>Vibrio parahaemolyticus</I>

“…VopL (VPA1370), which has three Wiskott-Aldrich homology 2 domains, potently and directly facilitates the assembly of actin without any other eukaryotic factors (35). VopC (VPA1321) exhibits 38% homology to Escherichia coli cytotoxic necrotizing factor (34). But the role of these effectors in T3SS2-dependent fluid accumulation is unclear.…”

“…VopT (VPA1327) has ADP-ribosyltransferase (ADPRT) activity and ribosylates Ras, a member of the lowmolecular-weight G proteins. In addition, VopT is partially responsible for the T3SS2-dependent cytotoxicity observed in Caco-2 cells (34). VopL (VPA1370), which has three Wiskott-Aldrich homology 2 domains, potently and directly facilitates the assembly of actin without any other eukaryotic factors (35).…”

Antibiotic-Resistance Profiles and the Identification of the Ampicillin-Resistance Gene of Vibrio parahaemolyticus Isolated from Seawater

“…독 (TDH-related hemolysin, TRH), serine protease 및 type III secretion systems (TTSS1과 2)를 통해 분비되는 각종 effector 단백질 등이 보고되어 있으나 정확한 병원성 기작에 관한 설명은 아직도 많이 부족한 실정이다 (Honda and Iida, 1993;Lee et al, 2002;Makino et al, 2003;Park et al, 2004;Kodama et al, 2007;Kodama et al, 2008).…”