6okb

Prohead 2 of the phage T5Prohead 2 of the phage T5

6okb, resolution 6.70Å Show:Asymmetric Unit Biological Assembly Structural highlights 6okb is a 13 chain structure with sequence from Escherichia phage t5. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Experimental data: Check Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [CAPSD_BPT5] Major capsid protein that self-associates to form 120 hexamers and 11 pentamers, building the T=13 icosahedral capsid which about 860 Angstroms in diameter. 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. The capsid gains its final stability through the reorganization of the subunits that takes place upon expansion. DNA encapsidation through the portal triggers capsid expansion and the binding of the decoration protein to the capsid exterior. Publication Abstract from PubMed The large (90-nm) icosahedral capsid of bacteriophage T5 is composed of 775 copies of the major capsid protein (mcp) together with portal, protease, and decoration proteins. Its assembly is a regulated process that involves several intermediates, including a thick-walled round precursor prohead that expands as the viral DNA is packaged to yield a thin-walled and angular mature capsid. We investigated capsid maturation by comparing cryoelectron microscopy (cryo-EM) structures of the prohead, the empty expanded capsid both with and without decoration protein, and the virion capsid at a resolution of 3.8 A for the latter. We detail the molecular structure of the mcp, its complex pattern of interactions, and their evolution during maturation. The bacteriophage T5 mcp is a variant of the canonical HK97-fold with a high level of plasticity that allows for the precise assembly of a giant macromolecule and the adaptability needed to interact with other proteins and the packaged DNA. Capsid expansion of bacteriophage T5 revealed by high resolution cryoelectron microscopy.,Huet A, Duda RL, Boulanger P, Conway JF Proc Natl Acad Sci U S A. 2019 Oct 15;116(42):21037-21046. doi:, 10.1073/pnas.1909645116. Epub 2019 Oct 2. PMID:31578255 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.