Project description:The genus Yersinia comprises 19 species of which three are known as human and animal pathogens. Some species display toxicity toward invertebrates using the so-called toxin complex (TC) and/or determinants that are not yet known. Recent studies showed a remarkable variability of insecticidal activities when representatives of different Yersinia species (spp.) were subcutaneously injected into the greater wax moth, Galleria mellonella. Here, we demonstrate that Y. intermedia and Y. frederiksenii are highly toxic to this insect. A member of Y. Enterocolitica phylogroup 1B killed G. mellonella larvae with injection doses of approximately 38 cells only, thus resembling the insecticidal activity of Photorhabdus luminescens. The pathogenicity Yersinia spp. displays toward the larvae was higher at 15°C than at 30°C and independent of the TC. However, upon subtraction of all genes of the low-pathogenic Y. enterocolitica strain W22703 from the genomes of Y. intermedia and Y. frederiksenii, we identified a set of genes that may be responsible for the toxicity of these two species. Indeed, a mutant of Y. frederiksenii lacking yacT, a gene that encodes a protein similar to the heat-stable cytotonic enterotoxin (Ast) of Aeromonas hydrophila, exhibited a reduced pathogenicity toward G. mellonella larvae and altered the morphology of hemocytes. The data suggests that the repertoire of virulence determinants present in environmental Yersinia species remains to be elucidated.
Project description:Yersinia enterocolitica-like strains are usually understudied. In this work, we reported the draft genome sequences of two Yersinia frederiksenii, two Yersinia intermedia, and two Yersinia kristensenii strains isolated from humans, animals, food, and the environment in Brazil. These draft genomes will provide better molecular characterizations of these species.
Project description:Some strains of Serratia entomophila and S. proteamaculans cause amber disease of the grass grub Costelytra zealandica (Coleoptera: Scarabaeidae). Three genes required for virulence, sepABC, are located on a large plasmid, pADAP. Sequence analysis suggests that the sepABC gene cluster may be part of a horizontally mobile region. This study presents evidence for the putative mobility of the sep genes of pADAP. Southern blot analysis showed that orthologues of the sep genes reside on plasmids within S. entomophila, S. liquefaciens, S. proteamaculans, and a plasmid from Yersinia frederiksenii. Three plasmids hybridized to the pADAP sep virulence-associated region but not the pADAP replication and conjugation regions. Subsequent DNA sequence analysis of the Y. frederiksenii sep-like genes, designated tcYF1 and tcYF2, showed that they had 88% and 87% DNA identity to sepA and sepB, respectively. These results indicate that the sep genes are part of a discrete horizontally mobile region.
Project description:A novel colicin type, designated colicin Fy, was found to be encoded and produced by the strain Yersinia frederiksenii Y27601. Colicin Fy was active against both pathogenic and nonpathogenic strains of the genus Yersinia. Plasmid YF27601 (5,574 bp) of Y. frederiksenii Y27601 was completely sequenced. The colicin Fy activity gene (cfyA) and the colicin Fy immunity gene (cfyI) were identified. The deduced amino acid sequence of colicin Fy was very similar in its C-terminal pore-forming domain to colicin Ib (69% identity in the last 178 amino acid residues), indicating pore forming as its lethal mode of action. Transposon mutagenesis of the colicin Fy-susceptible strain Yersinia kristensenii Y276 revealed the yiuR gene (ykris001_4440), which encodes the YiuR outer membrane protein with unknown function, as the colicin Fy receptor molecule. Introduction of the yiuR gene into the colicin Fy-resistant strain Y. kristensenii Y104 restored its susceptibility to colicin Fy. In contrast, the colicin Fy-resistant strain Escherichia coli TOP10F' acquired susceptibility to colicin Fy only when both the yiuR and tonB genes from Y. kristensenii Y276 were introduced. Similarities between colicins Fy and Ib, similarities between the Cir and YiuR receptors, and the detected partial cross-immunity of colicin Fy and colicin Ib producers suggest a common evolutionary origin of the colicin Fy-YiuR and colicin Ib-Cir systems.
Project description:BackgroundThe presence of beta-lactamases in Y. enterocolitica has been reported to vary with serovars, biovars and geographical origin of the isolates. An understanding of the beta-lactamases in other related species is important for an overall perception of antibiotic resistance in yersiniae. The objective of this work was to study the characteristics of beta-lactamases and their genes in strains of Y. intermedia and Y. frederiksenii, isolated from clinical and non-clinical sources in India.ResultsThe enzymes, Bla-A (a constitutive class A penicillinase) and Bla-B (an inducible class C cephalosporinase) were found to be present in all the clinical and non-clinical strains of Y. intermedia and Y. frederiksenii by double disc diffusion method. The results showed differential expression of Bla-A as indicated by presence/absence of synergy whereas expression of Bla-B was quite consistent. The presence of these enzymes was also reflected in the high minimum inhibitory concentrations, MIC50 (126-1024 mg/L) and MIC90 (256-1024 mg/L) of beta-lactam antibiotics against these species. Restriction fragment length polymorphism (RFLP) revealed heterogeneity in both blaA and blaB genes of Y. intermedia and Y. frederiksenii. The blaA gene of Y. intermedia shared significant sequence identity (87-96%) with blaA of Y. enterocolitica biovars 1A, 1B and 4. The sequence identity of blaA of Y. frederiksenii with these biovars was 77-79%. The sequence identity of blaB gene of Y. intermedia and Y. frederiksenii was more (85%) with that of Y. enterocolitica biovars 1A, 1B and 2 compared to other species viz., Y. bercovieri, Y. aldovae and Y. ruckeri. Isoelectric focusing data further revealed that both Y. intermedia and Y. frederiksenii produced Bla-A (pI 8.7) and "Bla-B like" (pI 5.5-7.1) enzymes.ConclusionBoth Y. intermedia and Y. frederiksenii showed presence of blaA and blaB genes and unequivocal expression of the two beta-lactamases. Limited heterogeneity was detected in blaA and blaB genes as judged by PCR-RFLP. Phylogenetic relationships showed that the two species shared a high degree of identity in their bla genes. This is the first study reporting characteristics of beta-lactamases and their genes in strains of Y. intermedia and Y. frederiksenii isolated from Asian region.