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Cryo-EM structure of the bacteriophage T4 portal protein assembly at near-atomic resolution.

Sun L, Zhang X, Gao S, Rao PA, Padilla-Sanchez V, Chen Z, Sun S, Xiang Y, Subramaniam S, Rao VB, Rossmann MG - Nat Commun (2015)

Bottom Line: However, the detailed structure of the portal protein remained unknown.The gp20 structure also verifies that the portal assembly is required for initiating head assembly, for attachment of the packaging motor, and for participation in DNA packaging.Comparison of the Myoviridae T4 portal structure with the known portal structures of φ29, SPP1 and P22, representing Podo- and Siphoviridae, shows that the portal structure probably dates back to a time when self-replicating microorganisms were being established on Earth.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Purdue University, 240S. Martin Jischke Drive, West Lafayette, Indiana 47907-2032, USA.

ABSTRACT
The structure and assembly of bacteriophage T4 has been extensively studied. However, the detailed structure of the portal protein remained unknown. Here we report the structure of the bacteriophage T4 portal assembly, gene product 20 (gp20), determined by cryo-electron microscopy (cryo-EM) to 3.6 Å resolution. In addition, analysis of a 10 Å resolution cryo-EM map of an empty prolate T4 head shows how the dodecameric portal assembly interacts with the capsid protein gp23 at the special pentameric vertex. The gp20 structure also verifies that the portal assembly is required for initiating head assembly, for attachment of the packaging motor, and for participation in DNA packaging. Comparison of the Myoviridae T4 portal structure with the known portal structures of φ29, SPP1 and P22, representing Podo- and Siphoviridae, shows that the portal structure probably dates back to a time when self-replicating microorganisms were being established on Earth.

No MeSH data available.


The gp20 structure with modelled dsDNA showing the key residues on the three loops (dashed black circles) that interact with DNA.The different portal protein subunits with their wing, stem, clip and crown domains are coloured green, blue, purple and orange, respectively.
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f6: The gp20 structure with modelled dsDNA showing the key residues on the three loops (dashed black circles) that interact with DNA.The different portal protein subunits with their wing, stem, clip and crown domains are coloured green, blue, purple and orange, respectively.

Mentions: Fitting of a B-DNA structure into the central channel of the dodecameric portal assembly shows that the contacts between any one gp20 molecule and the DNA are confined to three polypeptide loops separated from each other by approximately one DNA helical turn. These occur at the end of the clip domain (inner clip loop), at the loop near the amino end of α7 in the stem domain (channel loop) and at the tunnel loop (Fig. 6).


Cryo-EM structure of the bacteriophage T4 portal protein assembly at near-atomic resolution.

Sun L, Zhang X, Gao S, Rao PA, Padilla-Sanchez V, Chen Z, Sun S, Xiang Y, Subramaniam S, Rao VB, Rossmann MG - Nat Commun (2015)

The gp20 structure with modelled dsDNA showing the key residues on the three loops (dashed black circles) that interact with DNA.The different portal protein subunits with their wing, stem, clip and crown domains are coloured green, blue, purple and orange, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493910&req=5

f6: The gp20 structure with modelled dsDNA showing the key residues on the three loops (dashed black circles) that interact with DNA.The different portal protein subunits with their wing, stem, clip and crown domains are coloured green, blue, purple and orange, respectively.
Mentions: Fitting of a B-DNA structure into the central channel of the dodecameric portal assembly shows that the contacts between any one gp20 molecule and the DNA are confined to three polypeptide loops separated from each other by approximately one DNA helical turn. These occur at the end of the clip domain (inner clip loop), at the loop near the amino end of α7 in the stem domain (channel loop) and at the tunnel loop (Fig. 6).

Bottom Line: However, the detailed structure of the portal protein remained unknown.The gp20 structure also verifies that the portal assembly is required for initiating head assembly, for attachment of the packaging motor, and for participation in DNA packaging.Comparison of the Myoviridae T4 portal structure with the known portal structures of φ29, SPP1 and P22, representing Podo- and Siphoviridae, shows that the portal structure probably dates back to a time when self-replicating microorganisms were being established on Earth.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Purdue University, 240S. Martin Jischke Drive, West Lafayette, Indiana 47907-2032, USA.

ABSTRACT
The structure and assembly of bacteriophage T4 has been extensively studied. However, the detailed structure of the portal protein remained unknown. Here we report the structure of the bacteriophage T4 portal assembly, gene product 20 (gp20), determined by cryo-electron microscopy (cryo-EM) to 3.6 Å resolution. In addition, analysis of a 10 Å resolution cryo-EM map of an empty prolate T4 head shows how the dodecameric portal assembly interacts with the capsid protein gp23 at the special pentameric vertex. The gp20 structure also verifies that the portal assembly is required for initiating head assembly, for attachment of the packaging motor, and for participation in DNA packaging. Comparison of the Myoviridae T4 portal structure with the known portal structures of φ29, SPP1 and P22, representing Podo- and Siphoviridae, shows that the portal structure probably dates back to a time when self-replicating microorganisms were being established on Earth.

No MeSH data available.