Yersinia pseudotuberculosis

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Yersinia pseudotuberculosis
Infectious disease

Yersinia pseudotuberculosis
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Enterobacterales
Family: Yersiniaceae
Genus: Yersinia
Species:
Y. pseudotuberculosis
Binomial name
Yersinia pseudotuberculosis
(Pfeiffer 1889)
Smith & Thal 1965

Yersinia pseudotuberculosis is a

bacterium that causes Far East scarlet-like fever in humans, who occasionally get infected zoonotically, most often through the food-borne route.[1] Animals are also infected by Y. pseudotuberculosis. The bacterium is urease
positive.

Pathogenesis

In animals, Y. pseudotuberculosis can cause

lymph nodes
.

In humans, symptoms of

bacteremia
).

Far East scarlet-like fever usually becomes apparent five to 10 days after exposure and typically lasts one to three weeks without treatment. In complex cases or those involving

aminoglycosides, tetracycline, chloramphenicol, or a cephalosporin
may all be effective.

The recently described syndrome "Izumi-fever" has been linked to infection with Y. pseudotuberculosis.[2]

The symptoms of fever and abdominal pain mimicking appendicitis (actually from mesenteric lymphadenitis)

Y. pestis at only 10 CFU.[6]

Relationship to Y. pestis

Genetically, the pathogen causing plague, Y. pestis, is very similar to Y. pseudotuberculosis. The plague appears to have diverged from Y. pseudotuberculosis relatively recently - about 1,500 to 20,000 years ago, and shortly before the first historically recorded outbreaks in humans.[7] A 2015 paper in Cell argued for a divergence around 6,000 years ago.[8] These modern estimates differ dramatically from earlier suggestions in popular scientific literature which claimed that Y. pestis evolved in rodents "millions of years ago."[9]

Virulence factors

To facilitate attachment, invasion, and colonization of its host, this bacterium possesses many

virulence factors
. Superantigens, bacterial adhesions, and the actions of Yops (which are bacterial proteins once thought to be "Yersinia outer membrane proteins") that are encoded on the "[plasmid] for Yersinia virulence" – commonly known as the pYV – cause host pathogenesis and allow the bacteria to live parasitically.

pYV

The 70-kb pYV is critical to Yersinia's pathogenicity, since it contains many

genes known to encode virulence factors and its loss gives avirulence of all Yersinia species.[6] A 26-kb "core region" in the pYV contains the ysc genes, which regulate the expression and secretion of Yops.[5] Many Ysc proteins also amalgamate to form a type-III secretory apparatus, which secretes many Yops into the host cell cytoplasm with the assistance of the "translocation apparatus", constructed of YopB and YopD.[10][11] The core region also includes yopN, yopB, yopD, tyeA, lcrG, and lcrV, which also regulate Yops gene expression and help to translocate secretory Yops to the target cell.[5] For example, YopN and TyeA are positioned as a plug on the apparatus so only their conformational change, induced by their interaction with certain host cell membrane proteins, will cause the unblocking of the secretory pathway.[5][12] Secretion is regulated in this fashion so that proteins are not expelled into the extracellular matrix and elicit an immune response
. Since this pathway gives secretion selectivity, it is a virulence factor.

Effector Yops

In contrast to the ysc and yop genes listed above, the Yops that act directly on host cells to cause cytopathologic effects – "effector Yops" – are encoded by pYV genes external to this core region.

amino acids.[4]
LcrV, YopQ, YopE, YopT, YopH, YpkA, YopJ, YopM, and YadA are all secreted by the type-III secretory pathway.
DNA supercoiling around the virF gene, changes conformation, allowing for virF expression, which then up-regulates the Yop regulon.[25]

Adhesion

Y. pseudotuberculosis adheres strongly to intestinal cells via chromosomally encoded proteins

integrins.[26] Through this binding, the integrins cluster, thereby activating FAK, and causing a corresponding reorganization of the cytoskeleton.[4][26] Subsequent internalization of bound bacteria occurs when the actin-depolymerising Yops are not being expressed.[12] The protein encoded on the "attachment invasion locus" named Ail also bestows attachment and invasive abilities upon Yersiniae[27] while interfering with the binding of complement on the bacterial surface.[28] To increase binding specificity, the fibrillar pH6 antigen targets bacteria to target intestinal cells only when thermoinduced.[29]

Superantigens

Certain strains of Yersinia pseudotuberculosis express a superantigenic exotoxin, YPM, or the Y. pseudotuberculosis-derived mitogen, from the chromosomal ypm gene.

antibodies neutralizes YPM toxicity in vivo,[30] these cytokines are largely responsible for the damage caused indirectly by the exotoxin. Strains that carry the exotoxin gene are rare in Western countries, where the disease, when at all apparent, manifests itself largely with minor symptoms, whereas more than 95% of strains from Far Eastern countries contain ypm[33] and are correlated with Izumi fever and Kawasaki disease.[34]
Although the superantigen poses the greatest threat to host health, all virulence factors contribute to Y. pseudotuberculosis viability in vivo and define the bacterium’s pathogenic characteristics. Y. pseudotuberculosis can live extracellularly due to its formidable mechanisms of phagocytosis and
opsonisation resistance through the expression of Yops and the type III pathway;[11] yet, by limited pYV action, it can populate host cells, especially macrophages, intracellularly to further evade immune responses and be disseminated throughout the body.[35]

YpM
SCOP2
1pm4 / SCOPe / SUPFAM
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary

Function

Yersinia pseudotuberculosis-derived mitogens (YpM) are

cytokines
.

Structure

Members of this family of Yersinia pseudotuberculosis

tumour necrosis factor and viral capsid proteins. This suggests a possible evolutionary relationship.[36]

Subfamilies

Some highly similar homologous variants of YPM have been characterized, including YPMa, YPMb, and YPMc.

small non-coding RNA

Numerous bacterial small non-coding RNAs have been identified to play regulatory functions. Some can regulate the virulence genes. 150 unannotated sRNAs were identified by sequencing of Y. pseudotuberculosis RNA libraries from bacteria grown at 26 °C and 37 °C, suggesting they may play a role in pathogenesis.[37] By using single-molecule fluorescence in situ hybridisation smFISH technique it was shown that the number of YSR35 RNA increased 2.5 times upon temperature shift from 25 °C to 37 °C.[38] Another study uncovered that a temperature-induced global reprogramming of central metabolic functions are likely to support intestinal colonization of the pathogen. Environmentally controlled regulatory RNAs coordinate control of metabolism and virulence allowing rapid adaptation and high flexibility during life-style changes.[39] High-throughput RNA structure probing identified many thermoresponsive RNA structures.[40]

See also

References

  1. ISBN 978-0-8385-8529-0
    .
  2. ^ Jani, Asim (2003). "Pseudotuberculosis (Yersina)". Retrieved 2006-03-04.
  3. ^
    ISBN 978-0-08-045698-0
    .
  4. ^
    ISBN 978-0-203-91206-5
    .
  5. ^
    ISBN 978-1555812652
    .
  6. ^
    PMID 6195719
    .
  7. PMID 10570195
    .
  8. PMID 26496604
    .
  9. ISBN 9780684822709
    .
  10. PMID 9882687
    .
  11. ^
    PMID 9841674
    .
  12. ^
    PMID 10930402
    .
  13. PMID 10506187
    .
  14. PMID 9171345
    .
  15. S2CID 46632209
    .
  16. PMID 9188492
    .
  17. PMID 9811856
    .
  18. S2CID 4347737
    .
  19. PMID 9573064
    .
  20. PMID 8132332
    .
  21. PMID 8335343
    .
  22. PMID 8132334
    .
  23. PMID 8975933
    .
  24. S2CID 40096958
    .
  25. PMID 7893133
    .
  26. ^ a b Miller, V. (1992). "Yersinia invasion genes and their products". ASM News. 58: 26–33.
  27. PMID 1565652
    .
  28. S2CID 33124727
    .
  29. PMID 9159409
    .
  30. ^
    PMID 8409410
    .
  31. PMID 12756744
    .
  32. PMID 8586739
    .
  33. PMID 11574570
    .
  34. PMID 9440199
    .
  35. PMID 1468533
    .
  36. PMID 14725774
    .
  37. PMID 21876162
    .
  38. S2CID 18708152
    .
  39. PMID 25816203
    .
  40. PMID 27298343
    .

External links

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