Mutated coronavirus variant: What is spike protein and why is it so important?

The new variant brings several unusual changes to the spike protein compared to other closely related versions.

In the acute phase of the immune response, the researchers noticed higher levels of antibodies in subjects with more severe disease. Image credit: fotograzia / Getty Images

The emergence of a new variant coronavirus has sparked renewed interest in a portion of the virus known as the protein class. The new variant brings a few unusual changes to the spike protein compared to other closely related versions – and that’s one of the reasons why it’s more worrying than the other, harmless virus changes we’ve noticed before. New mutations can change the biochemistry of the spike and could affect how transmissible the virus is.

The protein spike is also the basis of electricity COVID-19 vaccines, which seek to create an immune response to them. But what exactly is spike protein and why is it so important?

Cell conquerors

In the world of parasites, many bacterial or fungal pathogens can survive on their own without an infected host cell. But viruses can’t. Instead, they must enter cells to replicate, where they use the cell’s own biochemical machines to build new virus particles and spread to other cells or individuals.

Our cells have evolved to prevent such an intrusion. One of the main defenses that cell life has against an attacker is its outer coating which consists of a fatty layer that contains all the enzymes, proteins and DNA that make up a cell. Due to the biochemical nature of the fat, the outer surface is highly negatively charged and repelled. Viruses must cross this barrier to gain access to the cell.

Like cell life, coronavirus They themselves are surrounded by a fatty membrane known as an envelope. To enter the cell’s interior, enveloped viruses use proteins (or glycoproteins because they are often covered with slippery sugar molecules) to fuse their own membrane with the cell’s membrane and take over the cell.

Spike protein coronavirus es is one such viral glycoprotein. Ebola viruses have one, influenza virus two, and herpes simplex virus five.

(Read also: Mutant coronavirus strain found in the UK: Is it more dangerous, which means for the vaccine and answers to other common questions)

Spike architecture

The protein class consists of a linear chain of 1,273 amino acids, neatly folded into a structure dotted with up to 23 sugar molecules. Class proteins like to be held together, and three separate class molecules bind to each other to form a functional “trimeric” unit.

The spike can be divided into different functional units, known as domains, that meet different biochemical functions of proteins, such as binding to the target cell, fusing with the membrane, and allowing the spike to sit on the viral envelope.

The pointed SARS-CoV-2 protein is stuck on an approximately spherical virus particle, embedded in the envelope and protruding into space, ready to adhere to unsuspecting cells. It is estimated that there are approximately 26 trimmers with spikes per virus.

One of these functional units binds to a protein on the surface of our cells, called ACE2, which triggers the uptake of virus particles and eventually membrane fusion. The spike is also involved in other processes such as folding, structural stability, and immune evasion.

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Structure and cross-sectional view of man coronavirus . Displays a shape view coronavirus as well as a cross-sectional view. The figure shows the major elements including Spike S protein, HE protein, viral envelope, and helical RNA. Image credit: Wikipedia

Vaccine against spike protein

Because spike protein is crucial for the virus, many antiviral vaccines or drugs target viral glycoproteins.

For SARS-CoV-2, vaccines produced by Pfizer / BioNTech and Moderna instruct our immune system to make its own version of the protein class, which occurs shortly after immunization. The production of spikes within our cells then begins the process of producing protective antibodies and T cells.

One of the most troubling characteristics of the SARS-CoV-2 class protein is how it moves or changes over time during virus evolution. Encoded in the viral genome, a protein can mutate and change its biochemical properties as the virus evolves.

Most mutations will not be beneficial or will stop the work of spike protein or will not affect its function. But some can cause changes that give a new version of the virus a selective advantage, making it more transmissible or contagious.

One way this could happen is by mutating a portion of the spike protein that prevents the binding of protective antibodies to it. Another way would be to make the spikes more “sticky” to our cells.

This is why new mutations that change the way spikes work are particularly worrying – they can affect how we control the spread of SARS-CoV-2. New variants found in the UK and elsewhere have mutations on the spike and the parts of the protein involved in entering your cells.

Experiments will have to be conducted in the laboratory to determine whether – and how – these mutations significantly alter the jump and whether our current control measures will remain in place.

This article was published from Conversation under a Creative Commons license. Read on original article.

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