3c9i | pdb_00003c9i
Structure of P22 Tail-Needle GP26 Bound to Xenon Gas
Structural highlights
FunctionNEEDL_BPP22 Cell-perforating component and plug protein of the phage tail machine. Host cell membrane perforation allows viral DNA ejection. Together with gp4 and gp10, gp26 is required for stabilization of the condensed DNA within the capsid by plugging the hole through which the DNA enters.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe tail needle, gp26, is a highly stable homo-trimeric fiber found in the tail apparatus of bacteriophage P22. In the mature virion, gp26 is responsible for plugging the DNA exit channel, and likely plays an important role in penetrating the host cell envelope. In this article, we have determined the 1.98 A resolution crystal structure of gp26 bound to xenon gas. The structure led us to identify a calcium and a chloride ion intimately bound at the interior of alpha-helical core, as well as seven small cavities occupied by xenon atoms. The two ions engage in buried polar interactions with gp26 side chains that provide specificity and register to gp26 helical core, thus enhancing its stability. Conversely, the distribution of xenon accessible cavities correlates well with the flexibility of the fiber observed in solution and in the crystal structure. We suggest that small internal cavities in gp26 between the helical core and the C-terminal tip allow for flexible swinging of the latter, without affecting the overall stability of the protein. The C-terminal tip may be important in scanning the bacterial surface in search of a cell-envelope penetration site, or for recognition of a yet unidentified receptor on the surface of the host. Structural plasticity of the phage P22 tail needle gp26 probed with xenon gas.,Olia AS, Casjens S, Cingolani G Protein Sci. 2009 Mar;18(3):537-48. PMID:19241380[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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