Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
Structure of the T4 baseplate and its function in triggering sheath contraction.
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Atomic structures of the T4 baseplate in pre- and post-attachment states define the position of the six gp25 subunits at the baseplate-sheath junction and show how rotation of the gp25-(gp6)2-gp7 module initiates tail sheath contraction.
"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."
Deep research summary for Bacteriophage T4 gene 25 (gp25)
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gp25 is a structural baseplate wedge protein that functions as the sheath initiator to nucleate polymerization of the contractile tail sheath protein gp18 in its extended state.
"The strongest convergent conclusion from structural biology and assembly models is that **T4 gp25 is a structural baseplate wedge protein that also acts as the “sheath initiator” (nucleator)** for polymerization of the contractile tail sheath protein **gp18** in the extended (pre-infection) conformation."
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Six gp25 subunits accommodate the extended beta-strand arms of the first ring of gp18 sheath subunits via a donor-strand handshake interface.
"- “Six gp25 molecules must accommodate twelve long arms” from the first layer of sheath subunits, implying gp25 provides a scaffold that accepts donor-strand/exchange-like arms during early sheath assembly."
UniProtKB record for P09425 (VG25_BPT4)
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gp25 is an inner baseplate protein next to the tail tube that participates in sheath assembly and, as part of the gp25-(gp6)2-gp7 module, in triggering sheath contraction.
"Baseplate protein that is located next to the tail tube (inner baseplate). Involved in sheath assembly. The gp25-(gp6)2-gp7 module is involved in sheath contraction (PubMed:27193680)."
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gp25 interacts with gp53 and the (gp6)2-gp7 heterotrimeric module.
"Homodimer. Interacts with gp53 and with the (gp6)2-gp7 heterotrimeric molecule; The gp25-(gp6)2-gp7 module is involved in sheath contraction (PubMed:27193680)."
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gp25 is present in 6 copies per baseplate.
"Note=Present in 6 copies in the baseplate."