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Sample Preparation for Single Virion Atomic Force Microscopy and Super-resolution Fluorescence Imaging
Published on: January 2, 2014
Atomic force microscopy investigation of Mason-Pfizer monkey virus and human immunodeficiency virus type 1
Yu G Kuznetsov1, P Ulbrich, S Haubova
1Department of Molecular Biology and Biochemistry, University of California, Irvine, 560 SH, Irvine, CA 92697-3900, USA.
Abstract:
Particles of DeltaProCANC, a fusion of capsid (CA) and nucleocapsid (NC) protein of Mason-Pfizer monkey virus (M-PMV), which lacks the amino terminal proline, were reassembled in vitro and visualized by atomic force microscopy (AFM). The particles, of 83-84 nm diameter, exhibited ordered domains based on trigonal arrays of prominent rings with center to center distances of 8.7 nm. Imperfect closure of the lattice on the spherical surface was affected by formation of discontinuities. The lattice is consistent only with plane group p3 where one molecule is shared between contiguous rings. There are no pentameric clusters nor evidence that the particles are icosahedral. Tubular structures were also reassembled, in vitro, from two HIV fusion proteins, DeltaProCANC and CANC. The tubes were uniform in diameter, 40 nm, but varied in length to a maximum of 600 nm. They exhibited left handed helical symmetry based on a p6 hexagonal net. The organization of HIV fusion proteins in the tubes is significantly different than for the protein units in the particles of M-PMV DeltaProCANC.
Insights
In vitro reassembly of DeltaProCANC protein particles from Mason-Pfizer monkey virus revealed ordered trigonal arrays. Tubular structures formed from HIV fusion proteins showed distinct helical symmetry, differing from M-PMV protein organization.
Area of Science:
- Structural biology
- Biophysics
- Virology
Background:
- The capsid (CA) and nucleocapsid (NC) proteins of Mason-Pfizer monkey virus (M-PMV) are crucial for viral assembly.
- Understanding the self-assembly properties of viral proteins is key to deciphering viral structure and function.
Purpose of the Study:
- To investigate the in vitro reassembly and structural characteristics of M-PMV DeltaProCANC protein particles.
- To compare the assembly of M-PMV DeltaProCANC with fusion proteins from Human Immunodeficiency Virus (HIV).
Main Methods:
- In vitro reassembly of M-PMV DeltaProCANC protein particles.
- Visualization and structural analysis using Atomic Force Microscopy (AFM).
- In vitro reassembly and structural characterization of tubular structures from HIV fusion proteins.
Main Results:
- M-PMV DeltaProCANC particles formed ordered domains with trigonal arrays (plane group p3) and a diameter of 83-84 nm.
- Discontinuities in the lattice indicated imperfect closure on the spherical surface.
- HIV fusion proteins formed uniform 40 nm diameter tubes with left-handed helical symmetry (p6 hexagonal net).
Conclusions:
- The M-PMV DeltaProCANC protein self-assembles into particles with a unique trigonal lattice structure, not icosahedral.
- HIV fusion proteins assemble into helical tubes with a distinct organization compared to M-PMV particles.
- Structural differences highlight varied protein assembly mechanisms between different viruses.
