Chimeric infective particles expand species boundaries in phage inducible chromosomal island mobilization

Abstract:
Some mobile genetic elements spread among unrelated bacterial species through unknown mechanisms. Recently, we discovered that identical capsid-forming phage-inducible chromosomal islands (cf-PICIs), a new family of phage satellites, are present across multiple species and genera, raising questions about their widespread dissemination. Here we have identified and characterized a new biological entity enabling this transfer. Unlike other satellites, cf-PICIs produce their own capsids and package their DNA, relying solely on phage tails for transfer. Remarkably, cf-PICIs release non-infective, tail-less capsids containing their DNA into the environment. These subcellular entities then interact with phage tails from various species, forming chimeric particles that inject DNA into different bacterial species depending on the tail present. Additionally, we elucidated the structure of the tail-less cf-PICIs and the mechanism behind their unique capsid formation. Our findings illuminate novel mechanisms used by satellites to spread in nature, contributing to bacterial evolution and the emergence of new pathogens.

Speaker:
Prof José Penadés
Professor of Microbiology,
Imperial College London

Biography:
José Penadés is a microbiologist specializing in bacterial evolution and gene transfer mechanisms. His research has significantly advanced our understanding of how bacteria acquire and disseminate genetic material, impacting their adaptability and pathogenicity.

A key discovery from his lab is lateral transduction, a powerful gene transfer mechanism facilitated by bacteriophages, enabling the large-scale movement of bacterial chromosomal genes. He also identified Phage-Inducible Chromosomal Islands (PICIs), which hijack bacteriophages to spread genetic traits. Another major finding, lateral cotransduction, reveals how bacteria simultaneously transfer multiple genetic elements, aiding adaptation and antibiotic resistance.

Penadés’ work extends to bacterial virulence, showing how minimal mutations can alter host specificity. His studies on arbitrium, a bacteriophage communication system, further enhance our understanding of microbial evolution. His groundbreaking research has profound implications for public health, antibiotic resistance, and infectious disease control.