5ngj
From Proteopedia
Crystal structure of pb6, major tail tube protein of bacteriophage T5
Structural highlights
Function[TUBE_BPT5] Polymerizes to make up the central tail tube that is surrounded by the tail sheath protein (TSP). Tail tube protein polymerization takes place around the tape measure protein (TMP) and is probably directed by chaperone proteins. The tail is a stack of 40 trimeric rings of the TTP. Upon binding to host cell, the tail sheath contracts and the tail tube penetrates the host envelope. The tail tube is involved in viral genome delivery during ejection.[1] [2] Publication Abstract from PubMedThe vast majority of phages, bacterial viruses, possess a tail ensuring host recognition, cell wall perforation and safe viral DNA transfer from the capsid to the host cytoplasm. Long flexible tails are formed from the tail tube protein (TTP) polymerised as hexameric rings around and stacked along the tape measure protein (TMP). Here, we report the crystal structure of T5 TTP pb6 at 2.2 A resolution. Pb6 is unusual in forming a trimeric ring, although structure analysis reveals homology with all classical TTPs and related tube proteins of bacterial puncturing devices (type VI secretion system and R-pyocin). Structures of T5 tail tubes before and after interaction with the host receptor were determined by cryo-electron microscopy at 6 A resolution. Comparison of these two structures reveals that host-binding information is not propagated to the capsid through conformational changes in the tail tube, suggesting a role of the TMP in this information transduction process. Bacteriophage T5 tail tube structure suggests a trigger mechanism for Siphoviridae DNA ejection.,Arnaud CA, Effantin G, Vives C, Engilberge S, Bacia M, Boulanger P, Girard E, Schoehn G, Breyton C Nat Commun. 2017 Dec 5;8(1):1953. doi: 10.1038/s41467-017-02049-3. PMID:29209037[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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