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Bacteriophage HK97 Expansion Intermediate IVBacteriophage HK97 Expansion Intermediate IV
Structural highlights
FunctionCAPSD_BPHK7 Assembles to form an icosahedral capsid of 66 nm, with a T=7 laevo symmetry (PubMed:11000116, PubMed:21276801). Responsible for its self-assembly into a procapsid. The phage does not need to encode a separate scaffolfing protein because its capsid protein contains the delta domain that carries that function.[1] [2] [3] [4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMaturation of the bacteriophage HK97 capsid from a precursor (Prohead II) to the mature state (Head II) involves a 60 A radial expansion. The mature particle is formed by 420 copies of the major capsid protein organized on a T = 7 laevo lattice with each subunit covalently crosslinked to two neighbors. Well-characterized pH 4 expansion intermediates make HK97 valuable for investigating quaternary structural dynamics. Here, we use X-ray crystallography and cryo-EM to demonstrate that in the final transition in maturation (requiring neutral pH), pentons in Expansion Intermediate IV (EI-IV) reversibly sample 14 A translations and 6 degrees rotations relative to a fixed hexon lattice. The limit of this trajectory corresponds to the Head II conformation that is secured at this extent only by the formation of the final class of covalent crosslinks. Mutants that cannot crosslink or EI-IV particles that have been rendered incapable of forming the final crosslink remain in the EI-IV state. Capsid conformational sampling in HK97 maturation visualized by X-ray crystallography and cryo-EM.,Gan L, Speir JA, Conway JF, Lander G, Cheng N, Firek BA, Hendrix RW, Duda RL, Liljas L, Johnson JE Structure. 2006 Nov;14(11):1655-65. PMID:17098191[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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