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From Proteopedia
Bacteriophage T4 gp17 motor assembly based on crystal structures and cryo-EM reconstructions
Structural highlights
FunctionTERL_BPT4 Component of the molecular motor that translocates genomic DNA in empty capsid during DNA packaging. Heterodimerizes with small terminase protein to be docked on capsid portal protein. The latter forms a ring in which genomic DNA in translocated into the capsid. May have or induce an endonuclease activity to cleave the genome concatemer after encapsidation (By similarity). Evolutionary Conservation Checkto colour the structure by Evolutionary Conservation, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedViral genomes are packaged into "procapsids" by powerful molecular motors. We report the crystal structure of the DNA packaging motor protein, gene product 17 (gp17), in bacteriophage T4. The structure consists of an N-terminal ATPase domain, which provides energy for compacting DNA, and a C-terminal nuclease domain, which terminates packaging. We show that another function of the C-terminal domain is to translocate the genome into the procapsid. The two domains are in close contact in the crystal structure, representing a "tensed state." A cryo-electron microscopy reconstruction of the T4 procapsid complexed with gp17 shows that the packaging motor is a pentamer and that the domains within each monomer are spatially separated, representing a "relaxed state." These structures suggest a mechanism, supported by mutational and other data, in which electrostatic forces drive the DNA packaging by alternating between tensed and relaxed states. Similar mechanisms may occur in other molecular motors. The structure of the phage T4 DNA packaging motor suggests a mechanism dependent on electrostatic forces.,Sun S, Kondabagil K, Draper B, Alam TI, Bowman VD, Zhang Z, Hegde S, Fokine A, Rossmann MG, Rao VB Cell. 2008 Dec 26;135(7):1251-62. PMID:19109896[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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