Sandbox viralpackagingmotors

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This page is setup for Ojuewa to build her senior project for OU CHEM 4923

Contents

Viral Packaging

P4 Protein from Bacteriophage PH12 in complex with ADP 1w44

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One of the most important stage in the life cycle of all viruses is the encapsidation (packaging) of the viral genome. Many virus package their genome into preformed capsids using packaging motors powered by the hydrolysis of ATP. The hexameric ATPase P4 of dsRNA bacteriophage phi 12, located at the vertices of the icosahedral capsid is such a packaging motor. [1] P4 protein is a 35-kDa ssRNA packaging ATPase from dsRNA bacteriophages belonging to the Cystoviridae family. ( phi 6 - phi 12). These viruses use a packaging motor like RNA packaging motor that is powered by the hydrolysis of ATP to condense the nucleic acid into a confined space.

Structure

The RNA packaging motor is a straightforward machinery that consists of a portal protein (P4) hexamer. The crystal structure of the hexameric P4 protein is made of three sub-units, one-half of the hexameric molecule (hexamers encirlce the crystallographic 2-fold axes). Residues 196-206, 300-306, and the C-terminal segment 322-331are disordered in all subunits.

Image:Packaging .png (A) Packaging of ssRNA via P4 hexamer into the icosahedral procapsid (B) P4 hexamer structure (C) Subunit structure, RecA-like catalytic core is shown in red (RA), N-terminal safety pin in cyan (PIN), apical domain in magenta (AP) and C-terminal platform in green (CT). The safety pin stabilizes interacts with a neighboring subunit and stabilizes the hexamer. (D) A scheme of the three step packaging mechanism for a ssRNA precursor. [2] The P4 viral packaging motor is a sequential is a molecular machine that must complete several task in sequential order.

Function

The RNA packaging motor is a straightforward machinery that consists of a portal protein (P4) hexamer.

Energetics

The P4 protein provides energy for the RNA translocation.

Structural highlights

PDB 1W44 Atomic Snapshots of an RNA Packaging motor. Arg residue highlighted in magenta
PDB 1W44 Atomic Snapshots of an RNA Packaging motor. Arg residue highlighted in magenta


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References

  1. ↑ Mancini EJ, Kainov DE, Grimes JM, Tuma R, Bamford DH, Stuart DI. Atomic snapshots of an RNA packaging motor reveal conformational changes linking ATP hydrolysis to RNA translocation. Cell. 2004 Sep 17;118(6):743-55. PMID:15369673 doi:10.1016/j.cell.2004.09.007
  2. ↑ http://dx.doi.org/10.1080/17486700802168502
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