The impressive mess of molecules that take care of life as we know it that biologists somehow overlooked a whole class of them until recently.
The missed bit of biochemistry is neither rare nor difficult to find.
It’s just that nobody had the idea to search for it before.
Carolyn Bertozzi, a biochemist from Standford expressed her amazement with the discovery:
“It’s really a bombshell because the discovery suggests that there are biomolecular pathways in the cell that are completely unknown to us.”
Biologists have a decent grasp of the core molecular building blocks. There are proteins (muscle), carbohydrates (like starch), nucleic acids (DNA), and lipids (fats).
They are furthermore divided into subtypes – Sugars and cellulose are labelled as carbohydrates.
There are also mixes of those groups, like when different sugars merge with lipids in a red blood cell, resulting in the ABO blood types.
Glycans are chains of sugar molecules that latch onto fats and proteins via glycosylation to aid in their transportation through a cell or folding into the adequate shapes for their purpose.
They are also implied in numerous fundamental processes of biology like embryo development and pathogen recognition, according to Sciencealert.
The researchers, under the lead of biochemist Ryan Flynn currently at Boston Children’s Hospital, found out that glycans can also attach to non-coding RNAs.
The discovery came as a bit of a shocker because RNA was formerly believed to work only inside cells, inside their nucleus and fluid, while glycans are normally separated from them thanks to membranes present in a cell’s surface or organelles.
Bertozzi mentioned that, according to the textbooks, RNA and glycans live in two different worlds.
They figured that out by marking glycol molecules with sialic acid in lab cells and extracting their RNA.
It turned out that part of the purified RNA had a sialic acid-labelled sugar coating.
The team then discovered the glycoRNA within every cell they checked – both human and animal – species separated by hundreds of million years of evolution.
That suggests that the molecules may also have some core functionality among life forms on our planet.
Flynn and his colleagues then compared the RNA bits of glycoRNA against RNA databases and discovered that some of the molecules match RNAs that usually are related to diseases.
Bertozzi accentuated on the fact that a part of the RNAs modified by glycans to form glycoRNA has a strong history of being linked with autoimmune diseases.
It had previously been thought that the bits of RNA were usually inaccessible to our immune system as they were tucked safely away within our cells and only released when a cell dies.
Flynn explained that they discovered that GlycoRNAs are on the cell surface, similar to proteins and lipids.
According to them, that is excellent news because it means that glycoRNAs can be involved directly in cell-to0cell communication.
That process was formerly believed to be off0limits for RNAs.
We’re thinking a lot about this now but you could imagine scenarios where glycoRNAs may play roles in parallel to other cell surface biomolecules like glycoproteins/lipids but with different dynamics, stabilities, or configurations
— Ryan Flynn (@raflynn5) May 17, 2021
The capability of glycans to link straight to RNA seems unlikely, so the team speculated that a third, very small molecule might be present, working like glue.
