Cell Wang Fengbin et al. Analyze the evolution and assembly mechanism of lemon-type viruses

Editor-in-Chief | Xi After two years of global epidemics, I believe that the veterans who subscribe to BioArt are no longer unfamiliar with the virus
.

According to the structure of the virus, the common ones are columnar helical type such as "tobacco mosaic virus", icosahedral type, envelope type virus such as "new coronavirus", complex type such as "bacteriophage" and so on
.

If you think that there are only a few viruses on earth, you are indeed being a little sloppy
.

In fact, there are many strange viruses living in extreme environments to infect archaea, such as "lemon virus", "beer bottle virus" and so on
.

In the past 20 years, many scientists have tried to study the structure of the "lemon-type" virus, and the models are also varied.
Some whimsical physicists have drawn the "regular icosahedral extension model" with their unparalleled imagination to simulate the lemon-type virus.
Of course, no one believed the result; there were also crystallography veterans who crystallized the "capsid protein", and then built a model that looked a bit interesting, and then our research found that they crystallized the wrong protein
.

On March 23, 2022, Edward H.
Egelman of the University of Virginia and Mart Krupovic of the University of Paris collaborated (together as Fengbin Wang (Twitter @jerrynosnothing) and Virginija Cvirkaite-Krupovic) to publish the article Spindle-shaped archaeal viruses evolved from rod- shaped ancestors to package a larger genome
.

"Lemon-type" archaea virus "This is probably the hardest subject I've ever seen," Ed Egelman said.
"Of course I haven't done it yet," he continued
.

Friends who are familiar with cryo-electron microscopy should not be difficult to see that it is difficult to directly make lemon-shaped shells, and different curvatures make it difficult to reconstruct different particles together
.

So we first tried different conditions to "abuse" the virus, and found that after the virus spit out its genomic DNA, it would turn into a column by itself
.

Does this sound a bit familiar? Usually, when nothing is installed, it is columnar, and when a lot of things are installed, it becomes a lemon shape
.

Yes, I'm talking about balloons, you're thinking something else and you're wrong
.

After the virus became columnar, we captured 12 contiguous radii, with the middle radii reaching a resolution that was good enough to identify proteins directly from the viral genome
.

How did the radius of the "lemon virus" change under the cryo-electron microscope? We found that a very simple quasi-equivalence principle is actually used
.

This principle was proposed by biophysics legend Don Caspar in the 1960s for the "regular icosahedron" virus
.

The core idea is a sentence: "close is good enough
.

" Larger icosahedral viruses usually have many capsid proteins, all of which are in slightly different environments, but the proteins themselves are flexible enough to adapt to slightly different environments.

.

Here we see that we align the 12 experimentally detected models at the two proteins in red at the bottom, their local interactions are almost unchanged, but small local differences, after cumulative amplification, will lead to radius huge changes
.

The last soul question of the quasi-equivalence of "lemon-type virus" is, why does "lemon-type virus" have to be lemon-type, and what are the evolutionary benefits? Our conjecture is that lemon-type viruses can carry more genomes than columnar viruses using the same number of capsid eggs
.

In fact, we even found a columnar virus whose capsid protein looks very similar to lemon-type viruses.
We can even put known lemon-type viruses in a map and find that their genome size is indeed the same as the shape of the virus.
There is a strong correlation
.

Many scientists have been wondering why some lemon-type viruses have "tails" and some have been bulging all the time.
Our explanation is relatively simple, that is, some viruses carry too much DNA, and there is really no room for "tails"
.

The "Lemon Virus" appears to be the last unused map to evolve from a columnar virus, a tribute to Don Caspar, who passed away last November
.

Original link: https://doi.
org/10.
1016/j.
cell.
2022.
02.
019 Publisher: 11th reprint notice [Non-original article] The copyright of this article belongs to the author of the article, and you are welcome to forward and share it.
Reprinting is prohibited without permission.
The author has all legal rights, and violators will be prosecuted
.