Baseplate hub assembly protein gp28 of bacteriophage T4 required during late morphogenesis for the formation of the central hub of the tail baseplate. Acting as a low-abundance assembly factor that associates with gp27 in an early hub precursor, gp28 is essential for assembling a functional central baseplate plug onto which the six peripheral baseplate wedges circularize, but is absent from the final atomic structure of the mature baseplate.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0098003 viral tail assembly | IEA GO_REF:0000043 | ACCEPT | Reason: Genetic and morphogenesis experiments demonstrate that gp28 is an essential group II baseplate factor required for assembling the central hub of the bacteriophage T4 tail baseplate. Supporting Evidence: file:BPT4/28/28-uniprot.txt FUNCTION: Baseplate hub assembly chaperone involved in the tail assembly. file:BPT4/28/28-deep-research-falcon.md Cells infected with gene 28 amber mutants accumulated normal 15S arm complexes but produced only small amounts of organized 70S baseplate-like structures that were unstable and, critically, lacked the density at the very center of the baseplate when examined by electron microscopy. |
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Download this section (compressed HTML)Q: How does transient binding of gp28 to gp27 facilitate formation of the (gp5-gp27)3 central hub complex in vivo when recombinant gp5 and gp27 can co-assemble in heterologous expression systems?
Q: At which step of central hub maturation—incorporation of gp5, gp26, or the gp29 tape measure protein—is gp28 displaced from the hub precursor?
Experiment: Perform affinity pull-down and quantitative mass spectrometry using tagged gp28 in T4-infected Escherichia coli extracts carrying amber mutations in genes 5, 26, 27, 29, or 51 to map the exact assembly intermediate in which gp28 resides.
Experiment: Determine the crystal or NMR structure of recombinant gp28 alone and bound to gp27 to define the interaction surface and mechanism of hub precursor stabilization.
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