title: Phage encoded H-NS: a potential achilles heel in the bacterial defence system.
abstract: The relationship between phage and their microbial hosts is difficult to elucidate in complex natural ecosystems. Engineered systems performing enhanced biological phosphorus removal (EBPR), offer stable, lower complexity communities for studying phage-host interactions. Here, metagenomic data from an EBPR reactor dominated by Candidatus Accumulibacter phosphatis (CAP), led to the recovery of three complete and six partial phage genomes. Heat-stable nucleoid structuring (H-NS) protein, a global transcriptional repressor in bacteria, was identified in one of the complete phage genomes (EPV1), and was most similar to a homolog in CAP. We infer that EPV1 is a CAP-specific phage and has the potential to repress up to 6% of host genes based on the presence of putative H-NS binding sites in the CAP genome. These genes include CRISPR associated proteins and a Type III restriction-modification system, which are key host defense mechanisms against phage infection. Further, EPV1 was the only member of the phage community found in an EBPR microbial metagenome collected seven months prior. We propose that EPV1 laterally acquired H-NS from CAP providing it with a means to reduce bacterial defenses, a selective advantage over other phage in the EBPR system. Phage encoded H-NS could constitute a previously unrecognized weapon in the phage-host arms race.
authors.affiliation: Advanced Water Management Centre, The University of Queensland, St. Lucia, Queensland, Australia.
authors.forename: Connor T
authors.initials: CT
authors.lastname: Skennerton
authors.forename: Florent E
authors.initials: FE
authors.lastname: Angly
authors.forename: Mya
authors.initials: M
authors.lastname: Breitbart
authors.forename: Lauren
authors.initials: L
authors.lastname: Bragg
authors.forename: Shaomei
authors.initials: S
authors.lastname: He
authors.forename: Katherine D
authors.initials: KD
authors.lastname: McMahon
authors.forename: Philip
authors.initials: P
authors.lastname: Hugenholtz
authors.forename: Gene W
authors.initials: GW
authors.lastname: Tyson
mesh_terms: D001419:Bacteria / Q000821:virology*; D001426:Bacterial Proteins / Q000235:genetics*; D001435:Bacteriophages / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D016679:Genome, Viral; D020641:Polymorphism, Single Nucleotide
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria