Evolution and Virulence Contributions of the Autotransporter Proteins YapJ and YapK of Yersinia pestis CO92 and Their Homologs in Y. pseudotuberculosis IP32953

Abstract

<jats:title>ABSTRACT</jats:title><jats:p><jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Yersinia pestis</jats:named-content>, the causative agent of plague, evolved from the gastrointestinal pathogen<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Yersinia pseudotuberculosis</jats:named-content>. Both species have numerous type Va autotransporters, most of which appear to be highly conserved. In<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pestis</jats:named-content>CO92, the autotransporter genes<jats:italic>yapK</jats:italic>and<jats:italic>yapJ</jats:italic>share a high level of sequence identity. By comparing<jats:italic>yapK</jats:italic>and<jats:italic>yapJ</jats:italic>to three homologous genes in<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pseudotuberculosis</jats:named-content>IP32953 (YPTB0365, YPTB3285, and YPTB3286), we show that<jats:italic>yapK</jats:italic>is conserved in<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pseudotuberculosis</jats:named-content>, while<jats:italic>yapJ</jats:italic>is unique to<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pestis</jats:named-content>. All of these autotransporters exhibit &gt;96% identity in the C terminus of the protein and identities ranging from 58 to 72% in their N termini. By extending this analysis to include homologous sequences from numerous<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pestis</jats:named-content>and<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pseudotuberculosis</jats:named-content>strains, we determined that these autotransporters cluster into a YapK (YPTB3285) class and a YapJ (YPTB3286) class. The YPTB3286-like gene of most<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pestis</jats:named-content>strains appears to be inactivated, perhaps in favor of maintaining<jats:italic>yapJ</jats:italic>. Since autotransporters are important for virulence in many bacterial pathogens, including<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pestis</jats:named-content>, any change in autotransporter content should be considered for its impact on virulence. Using established mouse models of<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pestis</jats:named-content>infection, we demonstrated that despite the high level of sequence identity,<jats:italic>yapK</jats:italic>is distinct from<jats:italic>yapJ</jats:italic>in its contribution to disseminated<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pestis</jats:named-content>infection. In addition, a mutant lacking both of these genes exhibits an additive attenuation, suggesting nonredundant roles for<jats:italic>yapJ</jats:italic>and<jats:italic>yapK</jats:italic>in systemic<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pestis</jats:named-content>infection. However, the deletion of the homologous genes in<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Y. pseudotuberculosis</jats:named-content>does not seem to impact the virulence of this organism in orogastric or systemic infection models.</jats:p>

Adhesive Properties of YapV and Paralogous Autotransporter Proteins of Yersinia pestis

“…2B and C). Taken together, these results confirmed that the cloned yapV and yapK gene constructs were expressed in E. coli and, in agreement with data from previous studies, demonstrated attributes of autotransporter proteins (14,26,27,37).…”

“…In addition, whether the passenger domain of an autotransporter protein can be translocated or injected into the host cytosol remains to be demonstrated. In contrast, the adhesive properties of the three Yap proteins described here provide a reasonable explanation for the reduced dissemination of the corresponding Y. pestis mutants in murine models of plague (37). It remains to be examined whether these paralogous adhesins and the previously described Y. pestis adhesins are each temporally and spatially regulated in a particular sequential manner so as to modulate the attachment and spreading properties of this pathogen in different hosts and host tissues (49)(50)(51).…”

“…Although many autotransporter genes of Y. pestis CO92 were transcribed only at very low levels in murine models of plague (26), some were shown to be significantly more expressed, including yapK and yapJ, with both of their products improving bacterial dissemination in murine models of plague (15,16,26,37). The virulence properties that were responsible for this phenotype remained unknown.…”

“…Recent studies with a recombinant YapV protein showed that this protein is an autotransporter protein by localizing in the outer membrane and exposing part of itself on the bacterial surface (27). Earlier studies with the orthologous YapK and YapJ autotransporter proteins of strain CO92 used murine models of plague that highlighted their additive effect on increasing bacterial dissemination (26,37). However, the mechanism responsible for the latter phenotype was not investigated further.…”

“…Based on the deciphered Y. pestis KIM genome (32), 10 different ORFs for predicted autotransporter proteins, designated YapA, YapC, YapE to YapH, and YapK to YapN, were originally described. Several of these proteins were investigated in more detail in the same strain (14) and in strain CO92 (16,17,24,26,37). An originally unrecognized ORF for a predicted autotransporter protein present in KIM5 but absent in strain CO92 was later designated yapV (y3429) (27).…”