PMID:22797755

Citation	Cumby, N, Edwards, AM, Davidson, AR and Maxwell, KL (2012) The bacteriophage HK97 gp15 moron element encodes a novel superinfection exclusion protein. J. Bacteriol. 194:5012-9
Abstract	A phage moron is a DNA element inserted between a pair of genes in one phage genome that are adjacent in other related phage genomes. Phage morons are commonly found within phage genomes, and in a number of cases, they have been shown to mediate phenotypic changes in the bacterial host. The temperate phage HK97 encodes a moron element, gp15, within its tail morphogenesis region that is absent in most closely related phages. We show that gp15 is actively expressed from the HK97 prophage and is responsible for providing the host cell with resistance to infection by phages HK97 and HK75, independent of repressor immunity. To identify the target(s) of this gp15-mediated resistance, we created a hybrid of HK97 and the related phage HK022. This hybrid phage revealed that the tail tube or tape measure proteins likely mediate the susceptibility of HK97 to inhibition by gp15. The N terminus of gp15 is predicted with high probability to contain a single membrane-spanning helix by several transmembrane prediction programs. Consistent with this putative membrane localization, gp15 acts to prevent the entry of phage DNA into the cytoplasm, acting in a manner reminiscent of those of several previously characterized superinfection exclusion proteins. The N terminus of gp15 and its phage homologues bear sequence similarity to YebO proteins, a family of proteins of unknown function found ubiquitously in enterobacteria. The divergence of their C termini suggests that phages have co-opted this bacterial protein and subverted its activity to their advantage.
Links	PubMed PMC3430355 Online version:10.1128/JB.00843-12
Keywords	Bacteriophages/growth & development; Bacteriophages/physiology; DNA, Viral/genetics; Viral Interference; Viral Proteins/metabolism; Virus Internalization; Virus Replication
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPHK7:Q9MCS4		GO:0098669: superinfection exclusion	ECO:0000315:		P		Evidence from figure 1: western blot and plaque assays show HK97 gp15 inhibiting phage infection when compared to a nonsense mutation. It shows this by adding a transformed plasmid into the host cells, one where it expresses gp15 and the other with a nonsense mutation. When expressing gp15 it prevents the growth of HK97 and inhibits the growth of several related phages but there is no similar effect in the nonsense mutation implying that gp15 is the cause of super infection exclusion.	complete CACAO 13126

References

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