4ZKU

P22 Tail Needle Gp26 crystallized at pH 10.0

Summary for 4ZKU

• Entry DOI: 10.2210/pdb4zku/pdb
• Related: 2POH 3C9I 4ZKP
• Descriptor: Tail needle protein gp26, CHLORIDE ION, CALCIUM ION, ... (4 entities in total)
• Functional Keywords: viral protein, p22, tail needle, membrane penetration
• Biological source: Enterobacteria phage P22
• Total number of polymer chains: 2
• Total formula weight: 50302.55

Authors

Sankhala, R.S.,Cingolani, G. (deposition date: 2015-04-30, release date: 2015-06-10, Last modification date: 2023-09-27)

Primary citation

Bhardwaj, A.,Sankhala, R.S.,Olia, A.S.,Brooke, D.,Casjens, S.R.,Taylor, D.J.,Prevelige, P.E.,Cingolani, G.
Structural Plasticity of the Protein Plug That Traps Newly Packaged Genomes in Podoviridae Virions.
J.Biol.Chem., 291:215-226, 2016

PubMed Abstract: Bacterial viruses of the P22-like family encode a specialized tail needle essential for genome stabilization after DNA packaging and implicated in Gram-negative cell envelope penetration. The atomic structure of P22 tail needle (gp26) crystallized at acidic pH reveals a slender fiber containing an N-terminal "trimer of hairpins" tip. Although the length and composition of tail needles vary significantly in Podoviridae, unexpectedly, the amino acid sequence of the N-terminal tip is exceptionally conserved in more than 200 genomes of P22-like phages and prophages. In this paper, we used x-ray crystallography and EM to investigate the neutral pH structure of three tail needles from bacteriophage P22, HK620, and Sf6. In all cases, we found that the N-terminal tip is poorly structured, in stark contrast to the compact trimer of hairpins seen in gp26 crystallized at acidic pH. Hydrogen-deuterium exchange mass spectrometry, limited proteolysis, circular dichroism spectroscopy, and gel filtration chromatography revealed that the N-terminal tip is highly dynamic in solution and unlikely to adopt a stable trimeric conformation at physiological pH. This is supported by the cryo-EM reconstruction of P22 mature virion tail, where the density of gp26 N-terminal tip is incompatible with a trimer of hairpins. We propose the tail needle N-terminal tip exists in two conformations: a pre-ejection extended conformation, which seals the portal vertex after genome packaging, and a postejection trimer of hairpins, which forms upon its release from the virion. The conformational plasticity of the tail needle N-terminal tip is built in the amino acid sequence, explaining its extraordinary conservation in nature.

PubMed: 26574546
DOI: 10.1074/jbc.M115.696260

Experimental method

X-RAY DIFFRACTION (2.5 Å)