The power of unbiased phenotypic screens – cellulose as a first receptor for the Schitoviridae phage S6 of Erwinia amylovora

Abstract

Summary Bacteriophages, host‐dependent replicative non‐cellular entities which significantly shape the microbial genomes and consequently physiological and ecological properties of the microbial populations are exploited to restrict plant, animal and human pathogens. Unravelling of phage characteristics aids the understanding of the basic molecular mechanisms of phage infections which can subsequently lead to the development of rationalized strategies to combat microbial pathogens. In an unbiased screen to investigate the molecular basis of infectivity of the fire blight pathogen Erwinia amylovora by the lytic Schitoviridae phage S6, the biofilm extracellular matrix component cellulose has been identified as a cyclic di‐GMP dependent first receptor required for infection with the phage to possess beta‐1,4‐glucosidases to degrade the exopolysaccharide. This absolute receptor dependency allows maintenance of a phage‐microbe equilibrium with a low bacterial density.

Pectobacterium versatile Bacteriophage Possum: A Complex Polysaccharide-Deacetylating Tail Fiber as a Tool for Host Recognition in Pectobacterial Schitoviridae

“…Escherichia phage G7C uses LPS as a receptor, although the adsorption apparatus comprises branched tail fibers (gp63.1 and gp66), where the first one contains the SGNH hydrolase domain and deacetylates the LPS [ 54 ]. LPS and outer polysaccharides were shown to serve as a primary receptor for P. parmentieri phage φA38 [ 55 ] and Erwinia amylovora phage S6 [ 56 , 57 ].…”

Bacterial Virus Forcing of Bacterial O-Antigen Shields: Lessons from Coliphages

“…It should be highlighted that, despite the relatively small OPS layer thickness (about 20-30 nm), the data suggest that the protective effect of this structure has a non-specific nature and is due to mechanical shielding of the OM surface. Nevertheless, the recognition of OPS itself or any other receptor exposed outside of the OPS layer (for example, flagella, pili and conserved polysaccharides such as ECA, NGR or even bacterial cellulose [113,114]) does not automatically explain how a virus penetrates the OPS barrier. The analysis of the data on functional and structural detail of infection mechanisms of different coliphages has, however, enabled us to propose that the most if not all the mechanisms phages use to move through the OPS layer rely on the generation of a mechanical force (Figure 4).…”