Molecular modeling often requires an understanding of how protein structures move and interact. One such critical motion is the SARS-CoV-2 spike opening motion, a key process enabling the virus to bind to human cells. This blog post will guide you through the computed spike opening motion and explain its importance in virology and structural biology.
The Significance of the Spike Opening Motion
The SARS-CoV-2 spike protein enables the virus to infect human cells by binding to the ACE2 receptor molecule on the cell’s surface. This process involves a transition from a closed (inactive) to an open (active) state, exposing the receptor-binding domain that connects with ACE2. Understanding this dynamic pathway is crucial for antibody research and vaccine development.
The spike consists of three identical S proteins forming a trimeric structure with C3 symmetry. Interestingly, only one of the three proteins binds to the ACE2 receptor at a time. The spike is also coated in sugar molecules, shielding much of its surface but leaving the receptor-binding domain exposed, making it a prime target for neutralizing antibodies.
How Motion Was Computed
SAMSON, the integrative molecular design platform, provides tools for visualizing and calculating such motions. Two well-known structures of the SARS-CoV-2 spike were used as starting points:
Using SAMSON modules, the pathway between these states was calculated via the following steps:
- Bond orders in sugars were adjusted and hydrogens were added for both states.
- The ARAP Interpolation Path module was used to create an initial pathway, interpolating motion between the open and closed states.
- A subsequent refinement of this trajectory was performed using the P-NEB module.
The computation outputs detailed trajectories that allow users to visualize the full spike motion sequence. These are available in multiple formats, such as PDB files, that can be integrated into further simulations.
Visualizing the Motion
Let’s take a closer look at the spike in motion. Below are three GIFs showing the transformation from the closed state (down) to the open state (up) from different perspectives:
Being able to see these trajectories makes it easier to analyze the spike’s behavior and understand its biological implications.
Exploring Trajectory Files
The computed motion can be downloaded below in different formats for use in your studies:
Each format provides a clear view of the spike transformation, offering significant value for modeling and simulation purposes.
To learn more about this fascinating motion and explore additional resources, visit the full documentation here: SARS-CoV-2 Spike Opening Tutorial.
*Note: SAMSON and all SAMSON Extensions are free for non-commercial use. You can get SAMSON at https://www.samson-connect.net.