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Structural Plasticity of the Protein Plug That Traps Newly Packaged Genomes in Podoviridae Virions.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2016 Jan 01; Vol. 291 (1), pp. 215-26. Date of Electronic Publication: 2015 Nov 16. - Publication Year :
- 2016
-
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.<br /> (© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Subjects :
- Bacteriophages chemistry
Circular Dichroism
Cryoelectron Microscopy
Crystallography, X-Ray
Deuterium Exchange Measurement
Hydrogen-Ion Concentration
Mass Spectrometry
Negative Staining
Protein Multimerization
Viral Tail Proteins ultrastructure
Genome, Viral
Podoviridae genetics
Viral Tail Proteins chemistry
Virion genetics
Virus Assembly
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 291
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 26574546
- Full Text :
- https://doi.org/10.1074/jbc.M115.696260