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Common and specific characteristics of the high-pathogenicity island of Yersinia enterocolitica
A Rakin1, C Noelting, S Schubert
1Max-von-Pettenkofer-Institüt für Hygiene und Medizinische Mikrobiologie, Ludwig Maximilians Universität München, 80336 Munich, Germany. rakin@m3401.mpk.med.uni-muenchen.de
Abstract:
Yersinia pestis, Y. pseudotuberculosis O:1, and Y. enterocolitica biogroup 1B strains carry a high-pathogenicity island (HPI), which mediates biosynthesis and uptake of the siderophore yersiniabactin and a mouse-lethal phenotype. The HPI of Y. pestis and Y. pseudotuberculosis (Yps HPI) are highly conserved in sequence and organization, while the HPI of Y. enterocolitica (Yen HPI) differs significantly. The 43,393-bp Yen HPI sequence of Y. enterocolitica WA-C, serotype O:8, was completed and compared to that of the Yps HPI of Y. pseudotuberculosis PB1, serotype O:1A. A common GC-rich region (G+C content, 57.5 mol%) of 30.5 kb is conserved between yersinia strains. This region carries genes for yersiniabactin biosynthesis, regulation, and uptake and thus can be considered the functional "core" of the HPI. In contrast, the second part of the HPI is AT rich and completely different in two evolutionary lineages of the HPI, being 12.8 kb in the Yen HPI and 5.6 kb in the Yps HPI. The variable part acquired one IS100 element in the Yps HPI and accumulated four insertion elements, IS1328, IS1329, IS1400, and IS1222, in the Yen HPI. The insertion of a 125-bp ERIC sequence modifies the structure of the promoter of the ybtA yersiniabactin regulator in the Yen HPI. In contrast to the precise excision of the Yps HPI in Y. pseudotuberculosis, the Yen HPI suffers imprecise deletions. The Yen HPI is stably integrated in one of the three asn tRNA copies in Y. enterocolitica biogroup 1B (serotypes O:8, O:13, O:20, and O:21), probably due to inactivation of the putative integrase. The 17-bp duplications of the 3' end of the asnT RNA are present in both Yersinia spp. The HPI attachment site is unoccupied in nonpathogenic Y. enterocolitica NF-O, biogroup 1A, serotype O:5. The HPI of Yersinia is a composite and widely spread genomic element with a highly conserved yersiniabactin functional "core" and a divergently evolved variable part.
Insights
The Yersinia high-pathogenicity island (HPI) contains a conserved core for yersiniabactin siderophore production. However, its variable regions show distinct evolutionary paths in Yersinia pestis and Yersinia enterocolitica.
Area of Science:
- Microbiology
- Genomics
- Molecular Biology
Background:
- Yersinia species harbor a high-pathogenicity island (HPI) crucial for yersiniabactin siderophore production and virulence.
- The HPI is conserved in Yersinia pestis and Yersinia pseudotuberculosis but differs significantly in Yersinia enterocolitica.
Purpose of the Study:
- To compare the sequence and organization of the Yersinia enterocolitica HPI (Yen HPI) with the Yersinia pestis/pseudotuberculosis HPI (Yps HPI).
- To elucidate the evolutionary divergence and structural characteristics of the HPI in different Yersinia species.
Main Methods:
- Whole-genome sequencing of the Yen HPI from Y. enterocolitica WA-C (O:8).
- Comparative sequence analysis of Yen HPI and Yps HPI from Y. pseudotuberculosis PB1 (O:1A).
- Identification and characterization of conserved and variable regions, insertion elements, and attachment sites.
Main Results:
- A conserved 30.5 kb GC-rich core region containing yersiniabactin-related genes is present in both Yen HPI and Yps HPI.
- The variable regions exhibit significant differences, with Yen HPI being larger (12.8 kb) and containing multiple insertion elements (IS1328, IS1329, IS1400, IS1222) compared to Yps HPI (5.6 kb, IS100).
- Yen HPI integrates into asn tRNA genes and undergoes imprecise deletions, unlike the precise excision of Yps HPI.
Conclusions:
- The Yersinia HPI is a composite genomic element with a conserved functional core and divergent variable regions.
- Evolutionary pressures have led to distinct structural modifications and integration/excision mechanisms in the Yen HPI and Yps HPI.
- Understanding HPI variation provides insights into Yersinia pathogenicity and evolution.