3p9a is a 9 chain structure with sequence from Enterobacteria phage p22. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Packaging of viral genomes into empty procapsids is powered by a large DNA-packaging motor. In most viruses, this machine is composed of a large (L) and a small (S) terminase subunit complexed with a dodecamer of portal protein. Here we describe the 1.75 A crystal structure of the bacteriophage P22 S-terminase in a nonameric conformation. The structure presents a central channel approximately 23 A in diameter, sufficiently large to accommodate hydrated B-DNA. The last 23 residues of S-terminase are essential for binding to DNA and assembly to L-terminase. Upon binding to its own DNA, S-terminase functions as a specific activator of L-terminase ATPase activity. The DNA-dependent stimulation of ATPase activity thus rationalizes the exclusive specificity of genome-packaging motors for viral DNA in the crowd of host DNA, ensuring fidelity of packaging and avoiding wasteful ATP hydrolysis. This posits a model for DNA-dependent activation of genome-packaging motors of general interest in virology.
Small Terminase Couples Viral DNA Binding to Genome-Packaging ATPase Activity.,Roy A, Bhardwaj A, Datta P, Lander GC, Cingolani G Structure. 2012 Jul 3. PMID:22771211[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ Roy A, Bhardwaj A, Datta P, Lander GC, Cingolani G. Small Terminase Couples Viral DNA Binding to Genome-Packaging ATPase Activity. Structure. 2012 Jul 3. PMID:22771211 doi:10.1016/j.str.2012.05.014
