3qr7 is a 2 chain structure with sequence from Enterobacteria phage p2. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Bacteriophages with contractile tails and the bacterial type VI secretion system have been proposed to use a special protein to create an opening in the host cell membrane during infection. These proteins have a modular architecture but invariably contain an oligonucleotide/oligosaccharide-binding (OB-fold) domain and a long beta-helical C-terminal domain, which initiates the contact with the host cell membrane. Using X-ray crystallography and electron microscopy, we report the atomic structure of the membrane-piercing proteins from bacteriophages P2 and varphi92 and identify the residues that constitute the membrane-attacking apex. Both proteins form compact spikes with a approximately 10A diameter tip that is stabilized by a centrally positioned iron ion bound by six histidine residues. The accumulated data strongly suggest that, in the process of membrane penetration, the spikes are translocated through the lipid bilayer without undergoing major unfolding.
Phage pierces the host cell membrane with the iron-loaded spike.,Browning C, Shneider MM, Bowman VD, Schwarzer D, Leiman PG Structure. 2012 Feb 8;20(2):326-39. PMID:22325780[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ Browning C, Shneider MM, Bowman VD, Schwarzer D, Leiman PG. Phage pierces the host cell membrane with the iron-loaded spike. Structure. 2012 Feb 8;20(2):326-39. PMID:22325780 doi:10.1016/j.str.2011.12.009
