View source for 8cfa


==HK97 Prohead II as part of a DNA packaging complex==
<SX load='8cfa' size='340' side='right' viewer='molstar' caption='[[8cfa]], [[Resolution|resolution]] 3.06&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8cfa]] is a 7 chain structure with sequence from [https://en.wikipedia.org/wiki/Hendrixvirus Hendrixvirus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8CFA OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8CFA FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.06&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=8cfa FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8cfa OCA], [https://pdbe.org/8cfa PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8cfa RCSB], [https://www.ebi.ac.uk/pdbsum/8cfa PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8cfa ProSAT]</span></td></tr>
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== Function ==
[https://www.uniprot.org/uniprot/CAPSD_BPHK7 CAPSD_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.<ref>PMID:11000116</ref> <ref>PMID:21276801</ref> <ref>PMID:7669350</ref> <ref>PMID:7723020</ref> 
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== Publication Abstract from PubMed ==
Double-stranded DNA viruses utilise machinery, made of terminase proteins, to package viral DNA into the capsid. For cos bacteriophage, a defined signal, recognised by small terminase, flanks each genome unit. Here we present the first structural data for a cos virus DNA packaging motor, assembled from the bacteriophage HK97 terminase proteins, procapsids encompassing the portal protein, and DNA containing a cos site. The cryo-EM structure is consistent with the packaging termination state adopted after DNA cleavage, with DNA density within the large terminase assembly ending abruptly at the portal protein entrance. Retention of the large terminase complex after cleavage of the short DNA substrate suggests that motor dissociation from the capsid requires headful pressure, in common with pac viruses. Interestingly, the clip domain of the 12-subunit portal protein does not adhere to C12 symmetry, indicating asymmetry induced by binding of the large terminase/DNA. The motor assembly is also highly asymmetric, showing a ring of 5 large terminase monomers, tilted against the portal. Variable degrees of extension between N- and C-terminal domains of individual subunits suggest a mechanism of DNA translocation driven by inter-domain contraction and relaxation.

Insights into a viral motor: the structure of the HK97 packaging termination assembly.,Hawkins DEDP, Bayfield OW, Fung HKH, Grba DN, Huet A, Conway JF, Antson AA Nucleic Acids Res. 2023 Jul 21;51(13):7025-7035. doi: 10.1093/nar/gkad480. PMID:37293963<ref>PMID:37293963</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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[[Category: Hendrixvirus]]
[[Category: Large Structures]]
[[Category: Antson AA]]
[[Category: Hawkins DEDP]]