Pathogenicity island

Definition

Pathogenicity islands (PAIs) are distinct genetic elements in the genomes of pathogenic bacteria that contain clusters of genes responsible for virulence. These regions are often acquired through horizontal gene transfer and can enhance the bacterium's ability to cause disease.

5 Must Know Facts For Your Next Test

1. PAIs often include genes for toxins, adhesion factors, and secretion systems that contribute to a bacterium's pathogenicity.
2. They are typically flanked by direct repeats, insertion sequences, or tRNA genes which facilitate their integration into the host genome.
3. The presence of PAIs can be detected through comparative genomics by identifying regions with a different G+C content compared to the rest of the genome.
4. PAIs are commonly found in gastrointestinal pathogens like Salmonella, E. coli, and Helicobacter pylori.
5. Some PAIs can be mobilized and transferred between bacteria through mechanisms such as conjugation or transformation.

Review Questions

• What types of genes are commonly found within pathogenicity islands?
• How do PAIs typically integrate into bacterial genomes?
• Name one method used to identify PAIs in bacterial genomes.

Related terms

Horizontal Gene Transfer: The movement of genetic material between organisms other than by vertical transmission (from parent to offspring).

Virulence Factors: Molecules produced by pathogens that contribute to the pathogenicity and facilitate infection and disease progression.

Comparative Genomics: A field of biological research where the genomic features of different organisms are compared.