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Identification and Molecular Characterisation of a Novel Mu-Like Bacteriophage, SfMu, of Shigella flexneri
Richa Jakhetia1, Naresh K Verma1
1Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia.
Abstract:
S. flexneri is the leading cause of bacillary dysentery in the developing countries. Several temperate phages originating from this host have been characterised. However, all S. flexneri phages known to date are lambdoid phages, which have the ability to confer the O-antigen modification of their host. In this study, we report the isolation and characterisation of a novel Mu-like phage from a serotype 4a strain of S. flexneri. The genome of phage SfMu is composed of 37,146 bp and is predicted to contain 55 open reading frames (orfs). Comparative genome analysis of phage SfMu with Mu and other Mu-like phages revealed that SfMu is closely related to phage Mu, sharing >90% identity with majority of its proteins. Moreover, investigation of phage SfMu receptor on the surface of the host cell revealed that the O-antigen of the host serves as the receptor for the adsorption of phage SfMu. This study also demonstrates pervasiveness of SfMu phage in S. flexneri, by identifying complete SfMu prophage strains of serotype X and Y, and remnants of SfMu in strains belonging to 4 other serotypes, thereby indicating that transposable phages in S. flexneri are not uncommon. The findings of this study contribute an advance in our current knowledge of S. flexneri phages and will also play a key role in understanding the evolution of S. flexneri.
Insights
Researchers discovered a novel Mu-like phage, SfMu, in Shigella flexneri (S. flexneri), a bacterium causing dysentery. This phage uses the host's O-antigen for entry and is widespread, offering new insights into S. flexneri phage evolution.
Area of Science:
- Microbiology
- Virology
- Genomics
Background:
- Shigella flexneri (S. flexneri) is a primary cause of bacillary dysentery globally.
- Existing characterized S. flexneri phages are lambdoid, capable of modifying host O-antigen.
- Limited knowledge exists regarding other phage types infecting S. flexneri.
Purpose of the Study:
- To isolate and characterize a novel phage from S. flexneri.
- To determine the genomic features and evolutionary relationships of the novel phage.
- To investigate the phage-host interaction and prevalence within S. flexneri populations.
Main Methods:
- Isolation and characterization of a novel phage from S. flexneri.
- Whole-genome sequencing and comparative genomic analysis.
- Host receptor binding assays and prevalence studies across different S. flexneri serotypes.
Main Results:
- A novel Mu-like phage, designated SfMu, was isolated from an S. flexneri serotype 4a strain.
- SfMu possesses a 37,146 bp genome with 55 predicted open reading frames and shows >90% protein identity to phage Mu.
- The O-antigen of S. flexneri serves as the receptor for SfMu adsorption, and SfMu prophages are prevalent in various S. flexneri serotypes.
Conclusions:
- This study introduces a novel Mu-like phage, SfMu, expanding the known diversity of S. flexneri phages beyond lambdoid types.
- SfMu's reliance on the O-antigen for host cell entry highlights a conserved interaction mechanism.
- The pervasiveness of SfMu indicates that transposable phages are common in S. flexneri, contributing to our understanding of bacterial-phage co-evolution.
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