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Pathogenicity island

May 01, 2024

Pathogenicity islands (PAIs), as termed in 1990, are a distinct class of genomic islands acquired by microorganisms through horizontal gene transfer.[1][2] Pathogenicity islands are found in both animal and plant pathogens.[2] Additionally, PAIs are found in both gram-positive and gram-negative bacteria.[2] They are transferred through horizontal gene transfer events such as transfer by a plasmid, phage, or conjugative transposon.[3] Therefore, PAIs contribute to microorganisms' ability to evolve.

One species of bacteria may have more than one PAI. For example, Salmonella has at least five.[citation needed]

An analogous genomic structure in rhizobia is termed a symbiosis island.

Properties edit

Pathogenicity islands (PAIs) are gene clusters incorporated in the genome, chromosomally or extrachromosomally, of pathogenic organisms, but are usually absent from those nonpathogenic organisms of the same or closely related species.[2][4][5] They may be located on a bacterial chromosome or may be transferred within a plasmid or can be found in bacteriophage genomes.[2] The GC-content and codon usage of pathogenicity islands often differs from that of the rest of the genome, potentially aiding in their detection within a given DNA sequence, unless the donor and recipient of the PAI have similar GC-content.[2]

PAIs are discrete genetic units flanked by direct repeats, insertion sequences or tRNA genes, which act as sites for recombination into the DNA. Cryptic mobility genes may also be present, indicating the provenance as transduction.[3] PAIs are flanked by direct repeats; the sequence of bases at two ends of the inserted sequence are the same. They carry functional genes, such as integrases, transposases, phagocytosis, or part of insertion sequences, to enable insertion into host DNA.[2] PAIs are often associated with tRNA genes, which target sites for this integration event.[2] They can be transferred as a single unit to new bacterial cells, thus conferring virulence to formerly benign strains.[4]

PAIs, a type of mobile genetic element, may range from 10-200 kb and encode genes which contribute to the virulence of the respective pathogen.[2] Pathogenicity islands carry genes encoding one or more virulence factors, including, but not limited to, adhesins, secretion systems (like type III secretion system), toxins, invasins, modulins, effectors, superantigens, iron uptake systems, o-antigen synthesis, serum resistance, immunoglobulin A proteases, apoptosis, capsule synthesis, and plant tumorigenesis via Agrobacterium tumefaciens.[2]

There are various combinations of regulation involving pathogenicity islands. The first combination is that the pathogenicity island contains the genes to regulate the virulence genes encoded on the PAI.[2] The second combination is that the pathogenicity island contains the genes to regulate genes located outside of the pathogenecity island.[2] Additionally, regulatory genes outside of the PAI may regulate virulence genes in the pathogenicity island.[2] Regulation genes typically encoded on PAIs include AraC-like proteins and two-component response regulators.[2]

PAIs can be considered unstable DNA regions as they are susceptible to deletions or mobilization.[2] This may be due to the structure of PAIs, with direct repeats, insertion sequences and association with tRNA that enables deletion and mobilization at higher frequencies.[3] Additionally, deletions of pathogenicity islands inserted in the genome can result in disrupting tRNA and subsequently affect the metabolism of the cell.[4]

Examples edit

References edit

  1. ^ Hacker, J; Bender, L; Ott, M; et al. (1990). "Deletions of chro- mosomal regions coding for fimbriae and hemolysins occur in vivo and in vitro in various extraintestinal Escherichia coli iso- lates". Microb. Pathog. 8 (3): 213–25. doi:10.1016/0882-4010(90)90048-U. PMID 1974320.
  2. ^ a b c d e f g h i j k l m n o Hacker, J; Kaper, JB (2000). "Pathogenicity islands and the evolution of microbes". Annu Rev Microbiol. 54: 641–679. doi:10.1146/annurev.micro.54.1.641. PMID 11018140. S2CID 1945976.
  3. ^ a b c d e Hacker, J.; Blum-Oehler, G.; Muhldorfer, I.; Tschape, H. (1997). "Pathogenecity islands of virulent bacteria: structure, function and impact on microbial evolution". Molecular Microbiology. 23 (6): 1089–1097. doi:10.1046/j.1365-2958.1997.3101672.x. PMID 9106201. S2CID 27524815.
  4. ^ a b c d Groisman E (1996). "Pathogenicity Islands: Bacterial Evolution in Quantum Leaps". Cell. 87 (5): 791–794. doi:10.1016/s0092-8674(00)81985-6. PMID 8945505. S2CID 173554.
  5. ^ Kaper JB, Hacker J, eds. 1999. Pathogenicity Islands and Other Mobile Virulence Elements. Washington, DC: Am. Soc. Microbiol. 1-11.
  6. ^ Nakano M. et al. 2001 Structural and sequence diversity of the pathogenicity island of uropathogenic Escherichia coli which encodes the USP protein
  7. ^ Lindsay, JA; Ruzin, A; Ross, HF; et al. (Jul 1998). "The gene for toxic shock toxin is carried by a family of mobile pathogenicity islands in Staphylococcus aureus". Molecular Microbiology. 29 (2): 527–43. doi:10.1046/j.1365-2958.1998.00947.x. PMID 9720870. S2CID 30680160.

External links edit

    May 01, 2024
    pathogenicity, island, pais, termed, 1990, distinct, class, genomic, islands, acquired, microorganisms, through, horizontal, gene, transfer, found, both, animal, plant, pathogens, additionally, pais, found, both, gram, positive, gram, negative, bacteria, they,. Pathogenicity islands PAIs as termed in 1990 are a distinct class of genomic islands acquired by microorganisms through horizontal gene transfer 1 2 Pathogenicity islands are found in both animal and plant pathogens 2 Additionally PAIs are found in both gram positive and gram negative bacteria 2 They are transferred through horizontal gene transfer events such as transfer by a plasmid phage or conjugative transposon 3 Therefore PAIs contribute to microorganisms ability to evolve One species of bacteria may have more than one PAI For example Salmonella has at least five citation needed An analogous genomic structure in rhizobia is termed a symbiosis island Contents 1 Properties 2 Examples 3 References 4 External linksProperties editPathogenicity islands PAIs are gene clusters incorporated in the genome chromosomally or extrachromosomally of pathogenic organisms but are usually absent from those nonpathogenic organisms of the same or closely related species 2 4 5 They may be located on a bacterial chromosome or may be transferred within a plasmid or can be found in bacteriophage genomes 2 The GC content and codon usage of pathogenicity islands often differs from that of the rest of the genome potentially aiding in their detection within a given DNA sequence unless the donor and recipient of the PAI have similar GC content 2 PAIs are discrete genetic units flanked by direct repeats insertion sequences or tRNA genes which act as sites for recombination into the DNA Cryptic mobility genes may also be present indicating the provenance as transduction 3 PAIs are flanked by direct repeats the sequence of bases at two ends of the inserted sequence are the same They carry functional genes such as integrases transposases phagocytosis or part of insertion sequences to enable insertion into host DNA 2 PAIs are often associated with tRNA genes which target sites for this integration event 2 They can be transferred as a single unit to new bacterial cells thus conferring virulence to formerly benign strains 4 PAIs a type of mobile genetic element may range from 10 200 kb and encode genes which contribute to the virulence of the respective pathogen 2 Pathogenicity islands carry genes encoding one or more virulence factors including but not limited to adhesins secretion systems like type III secretion system toxins invasins modulins effectors superantigens iron uptake systems o antigen synthesis serum resistance immunoglobulin A proteases apoptosis capsule synthesis and plant tumorigenesis via Agrobacterium tumefaciens 2 There are various combinations of regulation involving pathogenicity islands The first combination is that the pathogenicity island contains the genes to regulate the virulence genes encoded on the PAI 2 The second combination is that the pathogenicity island contains the genes to regulate genes located outside of the pathogenecity island 2 Additionally regulatory genes outside of the PAI may regulate virulence genes in the pathogenicity island 2 Regulation genes typically encoded on PAIs include AraC like proteins and two component response regulators 2 PAIs can be considered unstable DNA regions as they are susceptible to deletions or mobilization 2 This may be due to the structure of PAIs with direct repeats insertion sequences and association with tRNA that enables deletion and mobilization at higher frequencies 3 Additionally deletions of pathogenicity islands inserted in the genome can result in disrupting tRNA and subsequently affect the metabolism of the cell 4 Examples editThe P fimbriae island contains virulence factors such as haemolysin pili cytotoxic necrosing factor and uropathogenic specific protein USP 6 Yersinia pestis high pathogenicity island I has genes regulating iron uptake and storage Salmonella SP1 and SP2 sites 4 Rhodococcus equi virulence plasmid pathogenicity island encodes virulence factors for proliferation in macrophages The SaPI family of Staphylococcus aureus pathogenicity islands mobile genetic elements encode superantigens including the gene for toxic shock syndrome toxin and are mobilized at high frequencies by specific bacteriophages 7 Phage encoded Cholera toxin of Vibrio cholerae Diphtheria toxin of Corynebacterium diphtheriae Neurotoxins of Clostridium botulinum and Cytotoxin of Pseudomonas aeruginosa 3 Helicobacter pylori has two strains one being more virulent than the other due to the presence of the Cag pathogenicity island 3 References edit Hacker J Bender L Ott M et al 1990 Deletions of chro mosomal regions coding for fimbriae and hemolysins occur in vivo and in vitro in various extraintestinal Escherichia coli iso lates Microb Pathog 8 3 213 25 doi 10 1016 0882 4010 90 90048 U PMID 1974320 a b c d e f g h i j k l m n o Hacker J Kaper JB 2000 Pathogenicity islands and the evolution of microbes Annu Rev Microbiol 54 641 679 doi 10 1146 annurev micro 54 1 641 PMID 11018140 S2CID 1945976 a b c d e Hacker J Blum Oehler G Muhldorfer I Tschape H 1997 Pathogenecity islands of virulent bacteria structure function and impact on microbial evolution Molecular Microbiology 23 6 1089 1097 doi 10 1046 j 1365 2958 1997 3101672 x PMID 9106201 S2CID 27524815 a b c d Groisman E 1996 Pathogenicity Islands Bacterial Evolution in Quantum Leaps Cell 87 5 791 794 doi 10 1016 s0092 8674 00 81985 6 PMID 8945505 S2CID 173554 Kaper JB Hacker J eds 1999 Pathogenicity Islands and Other Mobile Virulence Elements Washington DC Am Soc Microbiol 1 11 Nakano M et al 2001 Structural and sequence diversity of the pathogenicity island of uropathogenic Escherichia coli which encodes the USP protein Lindsay JA Ruzin A Ross HF et al Jul 1998 The gene for toxic shock toxin is carried by a family of mobile pathogenicity islands in Staphylococcus aureus Molecular Microbiology 29 2 527 43 doi 10 1046 j 1365 2958 1998 00947 x PMID 9720870 S2CID 30680160 External links editBAC definition of pathogenicity Retrieved from https en wikipedia org w index php title Pathogenicity island amp 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