4bij | pdb_00004bij

Threading model of T7 large terminase

Loading... Status: waiting for Mol* initialization Structural highlights 4bij is a 5 chain structure with sequence from Bpt7. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 4bil Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [VDMB_BPT7] During the growth of this phage, DNA is synthesized as concatemers. During DNA packaging mature monomers are cut from the concatemers. Gp19 is a nonspecific endonuclease that cause double stranded breaks. Its activity is suppressible by either ATP or gp18. Publication Abstract from PubMed During bacteriophage morphogenesis DNA is translocated into a preformed prohead by the complex formed by the portal protein, or connector, plus the terminase, which are located at an especial prohead vertex. The terminase is a powerful motor that converts ATP hydrolysis into mechanical movement of the DNA. Here, we have determined the structure of the T7 large terminase by electron microscopy. The five terminase subunits assemble in a toroid which encloses a channel wide enough to accommodate dsDNA. The structure of the complete connector/terminase complex is also reported, revealing the coupling between the terminase and the connector forming a continuous channel. The structure of the terminase assembled into the complex showed a different conformation when compared to the isolated terminase pentamer. To understand in molecular terms the terminase morphological change we generated the terminase atomic model based on the crystallographic structure of its phage T4 counterpart. The docking of the threaded model in both terminase conformations showed that the transition between the two states can be achieved by rigid body subunit rotation in the pentameric assembly. The existence of two terminase conformations and its possible relation to the sequential DNA translocation may shed light into the molecular bases of the packaging mechanism of bacteriophage T7. Large terminase conformational change induced by connector binding in bacteriophage T7.,Dauden MI, Martin-Benito J, Sanchez-Ferrero JC, Pulido-Cid M, Valpuesta JM, Carrascosa JL J Biol Chem. 2013 Apr 30. PMID:23632014 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Terminase

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