Low copy expression vectors for use in Yersinia sp and related organisms
ABSTRACT In Yersinia, the most commonly used expression vectors for genetic studies such as gene complementation do not effectively allow for both induction and repression of gene expression. Additionally, there is no expression system available that can be induced in bacteria growing in vitro as well as in vivo, e.g. in eukaryotic cell lines or in living animal models. Here, we present a series of novel inducible low copy expression vectors that are well suited for use in the Yersinia species. Their tet operator/promoter/repressor system makes them distinct from other vectors, and gene transcription in bacteria can easily be induced by addition of anhydrotetracyline (ATc) either to the growth medium, to tissue culture medium during bacterial infections of cell lines or by injection into animals infected with bacteria. Researchers can choose between two different antibiotic resistances (kanamycin or spectinomycin), between two copy numbers (5 or 12-22) as well as between two different versions for expression from either the native RBS and ATG or RBS and ATG encoded in the plasmid. The whole vector series contains the same multi-cloning site from pBluescript II KS+ that allows for easy subcloning. Moreover, these vectors are built in a modular fashion that makes it simple to adapt them for other purposes. Finally, in addition to their use in Yersinia they are suitable for use in many other Enterobacteriaceae.
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ABSTRACT: The transcriptional regulator RovA positively regulates transcription of the Yersinia enterocolitica virulence gene inv. Invasin, encoded by inv, is important for establishment of Y. enterocolitica infection. However, a rovA mutant is more attenuated for virulence compared to an inv mutant, implying that RovA regulates additional virulence genes. When the Y. enterocolitica RovA regulon was defined by microarray analysis, YE1984 and YE1985 were among the genes identified as up-regulated by RovA. Since these genes are homologous to Xenorhabdus nematophila cytotoxin genes xaxA and xaxB, we named them yaxA and yaxB, respectively. In this work we demonstrate YaxAB impact the course of infection in the murine model. While a yaxAB mutant (ΔyaxAB) is capable of colonizing mice at the same level as wild type, it slightly delays the course of infection and results in differing pathology in the spleen. Further, we found that yaxAB encode a probable cytotoxin capable of lysing mammalian cells, that both YaxA and YaxB are required for cytotoxic activity, and that the two proteins associate. YaxAB-mediated cell death occurs via osmotic lysis through the formation of distinct membrane pores. In silico tertiary structural analysis identified predicted structural homology between YaxA and proteins in pore-forming toxin complexes from Bacillus cereus (HBL-B) and E. coli (HlyE). Thus, it appears that YaxAB function as a virulence factor by inducing cell lysis through the formation of pores in the host cell membrane. This characterization of YaxAB supports the hypothesis that RovA regulates expression of multiple virulence factors in Y. enterocolitica.Infection and immunity 09/2013; DOI:10.1128/IAI.00781-13 · 4.16 Impact Factor
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ABSTRACT: Autotransporter protein secretion represents one of the simplest forms of secretion across Gram-negative bacterial membranes. Once secreted, autotransporter proteins either remain tethered to the bacterial surface or are released following proteolytic cleavage. Autotransporters possess a diverse array of virulence-associated functions such as motility, cytotoxicity, adherence, and autoaggregation. To better understand the role of autotransporters in disease, our research is focused on the autotransporters of Yersinia pestis, the etiologic agent of plague. Y. pestis strain CO92 has nine functional conventional autotransporters, referred to as Yaps for Yersinia autotransporter proteins. Three Yaps have been directly implicated in virulence using established mouse models of plague infection (YapE, YapJ and YapK). While previous studies from our laboratory showed that most of the CO92 Yaps are cell associated, YapE and YapG are processed and released by the omptin protease Pla. In this study, we identify the Pla cleavage sites in YapG that result in many released forms of YapG in Y. pestis, but not in the evolutionarily related gastrointestinal pathogen, Yersinia pseudotuberculosis, which lacks Pla. Furthermore, we show that YapG does not contribute to Y. pestis virulence in established mouse models of bubonic and pneumonic infection. As Y. pestis has a complex life cycle involving a wide range of mammalian hosts and a flea vector for transmission, it remains to be elucidated whether YapG has a measureable role in any other stage of plague disease.Journal of Medical Microbiology 05/2013; 62. DOI:10.1099/jmm.0.056275-0 · 2.27 Impact Factor
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ABSTRACT: Autotransporters, the largest family of secreted proteins in Gram negative bacteria, perform a variety of functions, including adherence, cytotoxicity, and immune evasion. In Yersinia pestis the autotransporter YapE has adhesive properties and contributes to bubonic infection of the mouse model. Here, we demonstrate that omptin cleavage of Y. pestis YapE is required to mediate bacterial aggregation and adherence to eukaryotic cells. We demonstrate that omptin cleavage is specific for the Y. pestis and Y. pseudotuberculosis YapE orthologs but is not conserved in the Y. enterocolitica protein. We also show that cleavage of YapE occurs in Y. pestis but not in the enteric Yersinia species, and requires the omptin Pla (plasminogen activator protease), which is encoded on the Y. pestis-specific plasmid pPCP1. Together, these data show that post-translation modification of YapE appears to be specific to Y. pestis, was acquired along with the acquisition of pPCP1 during the divergence of Y. pestis from Y. pseudotuberculosis, and are the first evidence of a novel mechanism to regulate bacterial adherence.Molecular Microbiology 05/2013; DOI:10.1111/mmi.12273 · 5.03 Impact Factor