Heightened virulence of Yersinia is associated with decreased function of the YopJ protein

• Published in: bioRxiv
• Main Authors: Mares, Chris A, Lugo, Fernando P, Albataineh, Mohammad, Goins, Beth, Newton, Irene, Isberg, Ralph R, Bergman, Molly
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 09.08.2021
• Subjects: Animal models; Apoptosis; Cell death; Cytotoxicity; Divergence; Gene polymorphism; Hydrophobicity; Leucine; Macrophages; Pathogenesis; Phenylalanine; Positive selection; Proteins; Pseudotuberculosis; Strains (organisms); Suramin; Virulence; Yersinia; Yersiniosis; YopJ protein
• DOI: 10.1101/2021.03.22.436461

Despite the maintenance of YopP/J alleles throughout the human-pathogenic Yersinia lineage, the benefit of YopP/J-induced phagocyte death for Yersinia pathogenesis in animals is not obvious. To determine how sequence divergence of YopP/J has impacted Yersinia virulence, we examined protein polymorphisms in this Type III secreted effector protein across 17 Yersinia species, and tested the consequences of polymorphism in a murine model of sub-acute systemic yersiniosis. Our evolutionary analysis revealed that codon 177 has been subjected to positive selection - the Y. enterocolitica residue had been altered from a leucine to a phenylalanine in nearly all Y. pseudotuberculosis and Y. pestis strains examined. Despite being a minor change, as both leucine and phenylalanine have hydrophobic side chains, reversion of YopJF177 to the ancestral YopJL177 variant yielded a Y. pseudotuberculosis strain with enhanced cytotoxicity towards macrophages, consistent with previous findings. Surprisingly, expression of YopJF177L in the mildly attenuated ksgA- background rendered the strain completely avirulent in mice. Consistent with this hypothesis that YopJ activity indirectly relates to Yersinia pathogenesis in vivo, ksgA- strains lacking functional YopJ failed to kill macrophages but actually regained virulence in animals. Also, treatment with the anti-apoptosis drug suramin prevented YopJ-mediated macrophage cytotoxicity and enhanced Y. pseudotuberculosis virulence in vivo. Our results demonstrate that Yersinia-induced cell death is detrimental for bacterial pathogenesis in this animal model of illness, and indicate that positive selection has driven YopJ/P and Yersinia evolution towards diminished cytotoxicity and increased virulence, respectively. Competing Interest Statement The authors have declared no competing interest.