PMID:24443902

Citation	Auzat, I, Petitpas, I, Lurz, R, Weise, F and Tavares, P (2014) A touch of glue to complete bacteriophage assembly: the tail-to-head joining protein (THJP) family. Mol. Microbiol. 91:1164-78
Abstract	Bacteriophage SPP1 is a nanomachine built to infect the bacterium Bacillus subtilis. The phage particle is composed of an icosahedric capsid, which contains the viral DNA, and a long non-contractile tail. Capsids and tails are produced in infected cells by two distinct morphogenetic pathways. Characterization of the suppressor-sensitive mutant SPP1sus82 showed that it produces DNA-filled capsids and tails but is unable to assemble complete virions. Its purified tails have a normal length but lack a narrow ring that tapers the tail end found at the tail-to-head interface. The mutant is defective in production of gp17. The gp17 ring is exposed in free tails competent for viral assembly but becomes shielded in the final virion structure. Recombinant gp17 is active in an in vitro assay to stick together capsids and tails present in extracts of SPP1sus82-infected cells, leading to formation of infectious particles. Gp17 thus plays a fundamental role in the tail-to-head joining reaction, the ultimate step of virus particle assembly. This is the conserved function of gp17 and its structurally related proteins like lambda gpU. This family of proteins can also provide fidelity to termination of the tail tube elongation reaction in a subset of phages including coliphage lambda.
Links	PubMed Online version:10.1111/mmi.12526
Keywords	Bacillus Phages/physiology; Bacillus subtilis/virology; Protein Binding; Viral Structural Proteins/metabolism; Virus Assembly
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPSPP:TUBE		GO:0098005: viral head-tail joining	ECO:0000314:		P		An in-vitro complementation assay was used to study incorporation of gp17 during assembly of viral particles. Each extract was separately mixed with 4 different components; water, complete tails purified from SPP1sus31 with gp17, tails without gp17 purified from SPP1sus82, and purified gp17. After incubation, the titer of the progeny was calculated in Figure 7. The expected result was sus31 tails in both extracts allowed it to join to the capsids for virion assembly. When mixing SPP1sus82 tails without gp17 with SPP1sus45, virion particles assembled, suggesting endogenous gp17 was able to join head and tail. SPP1sus82 had a low titer, thus tails weren’t able to attach. Finally, purified gp17 mixed SPP1sus82 extracts was sufficient for tail to head stickage. This assay shows that gp17 is involved in binding to the tail and later attaching to the DNA-filled capsid.	complete CACAO 13181

References

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