Inner baseplate wedge protein gp53 of bacteriophage T4 present in six copies per virion (one per baseplate wedge) adjacent to the tail tube. Incorporated as the fifth component in the sequential wedge assembly pathway (gp10-gp7-gp8-gp6-gp53-gp25), gp53 acts as a bundle clamp that binds the (gp6)2-gp7 helical bundle across neighboring wedges to drive six-fold wedge circularization, recruits gp25, and contributes to the upper baseplate platform that interfaces with the contractile tail sheath.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0098003 viral tail assembly | IEA GO_REF:0000043 | ACCEPT | Reason: gp53 is an essential inner baseplate wedge protein that clamps neighboring (gp6)2-gp7 wedge complexes together to promote circularization of the six baseplate wedges and recruitment of gp25 during T4 tail assembly. Supporting Evidence: file:BPT4/53/53-uniprot.txt FUNCTION: Baseplate protein that is located next to the tail tube (inner baseplate). Involved in the tail assembly. file:BPT4/53/53-deep-research-falcon.md gp53 is a structural baseplate wedge protein whose primary function is to bind at the interface between neighboring wedges, promoting wedge–wedge association (“circularization”) into the hexagonal baseplate. |
| GO:0098015 virus tail | IEA GO_REF:0000043 | MODIFY | Reason: gp53 is specifically a structural component of the inner baseplate wedge rather than an unspecified tail region; the more specific child term GO:0098025 (virus tail, baseplate) is already annotated and directly supported by cryo-EM structures. Proposed replacements: virus tail, baseplate Supporting Evidence: file:BPT4/53/53-uniprot.txt FUNCTION: Baseplate protein that is located next to the tail tube (inner baseplate). Involved in the tail assembly. |
| GO:0098025 virus tail, baseplate | IEA GO_REF:0000043 | ACCEPT | Reason: gp53 is a core inner baseplate wedge subunit that interacts with gp25 and the (gp6)2-gp7 heterotrimer next to the tail tube. Supporting Evidence: file:BPT4/53/53-uniprot.txt Part of the baseplate macromolecular complex which consists of gp5, gp5.4, gp27 (central spike complex); gp6, gp25, gp53 (inner baseplate); gp7, gp8 (intermediate baseplate); gp9, gp10, gp11, gp12 (peripheral); gp48 and gp54 (proximal region of the tail tube). Interacts with gp25 and with the (gp6)2-gp7 heterotrimeric molecule. file:BPT4/53/53-deep-research-falcon.md In the Taylor et al. baseplate framework, gp53 is annotated as part of the wedge “core” and described functionally as a “bundle clamp” and “sheath platform”, emphasizing that it both stabilizes wedge architecture and contributes to the structural platform that interfaces with the sheath machinery. |
| GO:0098025 virus tail, baseplate | IDA PMID:27193680 Structure of the T4 baseplate and its function in triggering... | ACCEPT | Reason: Atomic-resolution cryo-EM reconstructions of the 6-MDa T4 baseplate resolve gp53 within the inner baseplate wedge core in both pre- and post-attachment states. Supporting Evidence: PMID:27193680 Here we present the atomic structure of the approximately 6-megadalton bacteriophage T4 baseplate in its pre- and post-host attachment states and explain the events that lead to sheath contraction in atomic detail. file:BPT4/53/53-uniprot.txt Part of the baseplate macromolecular complex which consists of gp5, gp5.4, gp27 (central spike complex); gp6, gp25, gp53 (inner baseplate); gp7, gp8 (intermediate baseplate); gp9, gp10, gp11, gp12 (peripheral); gp48 and gp54 (proximal region of the tail tube). Interacts with gp25 and with the (gp6)2-gp7 heterotrimeric molecule. |
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Download this section (compressed HTML)Q: How does binding of gp53 to the (gp6)2-gp7 heterotrimeric helical bundle allosterically create the high-affinity binding site for the sheath-initiator wedge subunit gp25?
Q: Which specific contacts between gp53 and the gp48/gp54 tail-tube junction rings are broken to release the inner baseplate from the central tube during sheath contraction?
Experiment: Compare high-resolution cryo-EM structures of recombinant gp10-gp7-gp8-gp6 wedge intermediates before and after gp53 addition to visualize the conformational clamping of the (gp6)2-gp7 bundle that drives spontaneous wedge circularization.
Experiment: Introduce targeted point mutations at the gp53–gp25 and gp53–gp48 interfaces to dissect how gp53 couples peripheral wedge expansion to release of the gp18 sheath.
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