The peptidoglycan-binding domain of a mycobacterial prophage-encoded LysinB reveals diverse approaches for domain conservation in hydrolases.

Mycobacteriophage-encoded LysinB enzymes target mycolyl ester linkages in mycolyl-arabinogalactan-peptidoglycan of mycobacterium hosts and generally exhibit a globular architecture. Here, we present the structural and functional characterization of a novel Mycobacterium fortuitum prophage-encoded modular LysinB (LysinB_MF), which contains the α/β hydrolase domain and a distinct peptidoglycan-binding domain (PGBD). The enzyme's active site features the conserved Ser-Asp-His catalytic triad common to esterases and forms a funnel-like topology.

Genomic analysis of five new mycobacteriophages belonging to the F, G, K, and P clusters.

Unlabelled: Mycobacterial infections are accountable for some of the most challenging diseases to treat in both humans and veterinary medicine, particularly with the increasing prevalence of multidrug-resistant (MDR) species. Bacteriophages (phages) are being actively investigated as a promising alternative to antibiotic therapy and mycobacteriophages, phages that infect mycobacteria, have recently been demonstrated to be effective candidates in phage therapy. Therefore, discovery and genomic characterisation of diverse phages capable of infecting and killing pathogenic mycobacteria are crucial steps in both monophage therapy and multi-phage therapy, where two or more phages are used in combination.

Discovery and characterization of a novel LysinB from F2 sub-cluster mycobacteriophage RitSun.

The escalating antibiotic resistance in mycobacterial species poses a significant threat globally, necessitating an urgent need to find alternative solutions. Bacteriophage-derived endolysins, which facilitate phage progeny release by attacking bacterial cell walls, present promising antibacterial candidates due to their rapid lytic action, high specificity and low risk of resistance development. In mycobacteria, owing to the complex, hydrophobic cell wall, mycobacteriophages usually synthesize two endolysins: LysinA, which hydrolyzes peptidoglycan; LysinB, which delinks mycolic acid-containing outer membrane and arabinogalactan, releasing free mycolic acid.

Insights into the genomic features and lifestyle of B1 subcluster mycobacteriophages.

Bacteriophages infecting Mycobacterium smegmatis mc155 are numerous and, hence, are classified into clusters based on nucleotide sequence similarity. Analyzing phages belonging to clusters/subclusters can help gain deeper insights into their biological features and potential therapeutic applications. In this study, for genomic characterization of B1 subcluster mycobacteriophages, a framework of online tools was developed, which enabled functional annotation of about 55% of the previously deemed hypothetical proteins in B1 phages.

Unlocking prophage potential: and experimental analysis of a novel LysinB containing a peptidoglycan-binding domain.

Endolysins are highly evolved bacteriophage-encoded lytic enzymes produced to damage the bacterial cell wall for phage progeny release. They offer promising potential as highly specific lytic proteins with a low chance of bacterial resistance. The diversity in lysin sequences and domain organization can be staggering.