Kalmar, D. | bioRxiv Science

bioRxiv2024

The branched receptor binding complex of Ackermannviridae phages promotes adaptative host recognition

Bacteriophages may express multiple receptor binding proteins, enabling the recognition of distinct and diverse bacterial receptors for infection of a broad range of strains. Ackermannviridae phages recognize diverse O-antigens or K-antigens as receptors by expressing multiple tail spike proteins (TSPs). These TSPs interact and form a branched protein complex protruding from the baseplate attached to the distal tail. Here, we aimed to mimic the evolution of the TSP complex by studying the acquisition of new TSPs without disrupting the functionality of the complex. Using kuttervirus phage S117 as a backbone, we demonstrated the acquisition of entire tsp genes from Kuttervirus and Agtrevirus phages within the Ackermannviridae family. A fifth TSP was designed to interact with the complex and provide new host recognition to expand the branched TSP complex. Interestingly, the acquisition of tsp5 resulted in new variants of the branched TSP complex due to the exchange or deletion of tsp genes. Overall, our study provides novel insight into the development of the branched TSP complex, enabling Ackermannviridae phages to adapt to new hosts.

microbiology↗

bioRxiv2023

Agtrevirus phage AV101 infect diverse extended spectrum β-lactamase E. coli by recognizing four different O-antigens

Bacteriophages in the Agtrevirus genus are known for expressing multiple tail spike proteins (TSPs), but little is known about their genetic diversity and host recognition apart from their ability to infect diverse Enterobacteriaceae species. Here we aim to determine the genetic differences that may account for the diverse host ranges of Agrevirus phages. We performed comparative genomics of 14 Agtrevirus and identified only a few genetic differences including genes involved in nucleotide metabolism. Most notably was the diversity of the tsp gene cluster, specifically in the receptor binding domains that were unique among most of the phages. We further characterized agtrevirus AV101 infecting nine diverse Extended Spectrum {beta}-lactamase (ESBL) E. coli and demonstrated that this phage encoded four unique TSPs among Agtrevirus. Purified TSPs formed translucent zones and inhibited AV101 infection of specific hosts, demonstrating that TSP1, TSP2, TSP3, and TSP4 recognize O8, O82, O153, and O159 O-antigens of ESBL E. coli, respectively. BLASTp analysis showed that the receptor binding domain of TSP1, TSP2, TSP3 and TSP4 are similar to TSPs encoded by E. coli prophages and distant related virulent phages. Thus, Agtrevirus may have gained their receptor binding domains by recombining with prophages or virulent phages. Overall, combining bioinformatic and biological data expands the understanding of TSP host recognition of Agtrevirus and give new insight into the origin and acquisition of receptor binding domains of Ackermannviridae phages. One sentence summaryAgtrevirus phage AV101 express four unique tail spike proteins that recognize different O-antigens of Extended Spectrum {beta}-Lactamase producing E. coli.

microbiology↗