YopM inhibits platelet aggregation and is necessary for virulence of Yersinia pestis in mice

Abstract

In Yersinia pestis KIM there are 11 Yops (yersinial outer membrane proteins) encoded by the low-Ca2" response virulence plasmid pCD1. Only YopM and YopN are found in easily detectable amounts in the culture medium. In our previous work, we characterized the yopM gene. In the present study, we constructed a YopMmutant to elucidate the role of YopM in the virulence of Y. pestis. A lacZYA sequence was inserted 126 base pairs downstream from the start codon of the yopM gene in pCD1. The YopMmutant had the same growth properties as the parent, Y. pestis KIM5-3001. The inserted lacZ gene was regulated by the promoter of the yopM gene. Accordingly, it was expressed strongly at 37°C in the absence of Ca2' and was decreased in expression when Ca2+ was present. Northern blot (RNA blot) analysis revealed that the yopM gene was in a monocistronic operon, suggesting that the yopM insertion mutation was unlikely to have polar effects on other genes. The YopMmutant had strongly decreased virulence in mice, with a 50% lethal dose of 3.4 x 105 CFU. Virulence was restored by the cloned yopM-containing 5.5-kilobase Hindlll F fragment of pCDl. However, supplying a cloned 1.57-kilobase fragment containing little more than the yopM structural gene caused the yopM mutant to signfficantly overexpress YopM and failed to restore virulence. The infection kinetics of the YopMmutant revealed growth in both spleens and livers from days 2 to 4 after infection, followed by a precipitous clearance of the bacteria. YopM-containing supernatant proteins of Y. pestis inhibited thrombinor ristocetin-induced platelet aggregation, whereas there was no inhibition by supernatant proteins from the YopM-Y. pestis mutant. Accordingly, YopM may prevent platelet-mediated events and serve as an important strategy for the yersiniae in the initial stages of a plague infection.

Yersinia outer proteins: Yops

“…This YopM-mediated scaffolding results in activation of kinases downstream of the Yersinia YopJ block in the MAPK pathways (see below) (McDonald et al, 2003). Although the role of YopM in pathogenesis remains unclear, it is important in a mouse model of infection because of decreased virulence in mice infected with a YopM null strain (Mulder et al, 1989;Leung et al, 1990).…”

An extracellular Leptospira interrogans leucine‐rich repeat protein binds human E‐ and VE‐cadherins

“…Other important pathogens also use LRR proteins to establish themselves in hosts. These bacterial LRR proteins can be effectors secreted directly into the host cell (Leung, Reisner, & Straley, 1990;Miao et al, 2002), or act as bacterial adhesins (Bierne et al, 2007;Bober, Mörgelin, Olin, von Pawel-Rammingen, & Collin, 2011).…”

Transcriptional responses of murine macrophages to infection with Yersinia enterocolitica

“…The function of YopM is enigmatic to date. It consists almost entirely of leucine-rich repeats (Evdokimov et al ., 2001) and has been shown to be essential for full virulence in mouse infection models (Leung et al ., 1990). It binds both thrombin and von Willebrand factor, but these properties are dispensable for virulence (Hines et al ., 2001).…”