Think back to the introductory biology class you took in high school. Perhaps you have learned about: organelleThey are small ‘organs’ inside cells that form compartments with individual functions.
For example, mitochondria produce energy, lysosomes recycle waste, and the nucleus stores DNA. Although each organelle has a different function, they are all similar in that they are all enclosed in a membrane.
Membrane-bound organelles were the textbook standard for how scientists thought cells were organized. Until I realized it in the mid-2000s Some organelles do not need to be surrounded by a membrane.
Since then, researchers have discovered many additional membraneless organelles that have significantly changed the way biologists think about chemistry and the origins of life.
I was introduced to cellular organelles, officially called ‘membraneless organelles’. biomolecular condensateA few years ago, students in my lab Unique staining was observed in the cell nuclei.
Without realizing it, we have actually been studying biomolecular condensates for many years. What I finally saw in that stain opened my eyes to a whole new world of cell biology.
Like a lava lamp
To understand what biomolecular condensates look like, imagine a lava lamp where the wax chunks inside fuse together, break apart, and fuse again. condensate formed in much the same wayAlthough it is not made of wax. Instead, clusters of intracellular proteins and genetic material, especially RNA molecules, condense into gel-like droplets.
Some proteins and RNA do this because they preferentially interact with each other instead of with their surroundings. This is very similar to how the wax globules in a lava lamp mix with each other rather than with the surrounding liquid. These condensates create a new microenvironment that attracts additional protein and RNA molecules, forming unique biochemical compartments within the cell.
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As of 2022, researchers have found that: 30 types of membraneless biomolecular condensates. In comparison, about a dozen classical membrane-bounded organelles are known.
Although easy to identify once you know what you are looking for, it is difficult to determine exactly what biomolecular condensates do. Some have well-defined roles, such as formation. germ cells, stress granules and Ribosomes that make proteins. However, many other products lack clear features.
Non-membrane-bound organelles can have more and more diverse functions than membrane-bound organelles. Learning about these unknown functions has implications for scientists’ fundamental understanding of how cells work.
Protein Structure and Function
Biomolecular condensates are challenging long-held beliefs about protein chemistry.
Since scientists first got a good look at this substance, Structure of myoglobin protein By the 1950s, it became clear that the structure was important for the ability to supply oxygen to muscles. Since then, the mantra of biochemists has been that protein structure equals protein function. Basically, proteins have a specific shape that allows them to perform their role.
Proteins that form biomolecular condensates violate this rule, at least partially, because they are disordered regions, meaning they have no defined shape. When researchers discovered the so-called Intrinsically disordered proteins, i.e. IDPsIn the early 1980s, they were initially confused by the fact that these proteins lacked a strong structure but were still able to perform specific functions.
Later they discovered it. IDPs tend to form condensates.. As is often the case in science, this discovery solved one of the mysteries about the role these unstructured, rogue proteins play in cells, and opened up another, deeper question: what biomolecular condensates actually are.
bacterial cell
Researchers also discovered: Biomolecular condensates of prokaryotesor bacterial cells, traditionally defined as containing no organelles. This discovery could have profound implications for how scientists understand the biology of prokaryotic cells.
only Bacterial protein 6% This compares to 30-40% of eukaryotic or non-bacterial proteins that have disordered regions lacking structure. However, scientists have discovered several biomolecular condensates in prokaryotic cells that are involved in a variety of cellular functions. including making break down RNA.
The presence of biomolecular condensates in bacterial cells means that these microorganisms are not simple bags of proteins and nucleic acids, but are actually more complex than previously recognized.
origin of life
Biomolecular condensates are also changing the way scientists think about the origins of life on Earth.
There is ample evidence that nucleotides, the building blocks of RNA and DNA, can very plausibly be made from common chemicals and universally common minerals, such as hydrogen cyanide and water, in the presence of a common energy source such as ultraviolet light or high temperatures. good night Silica and iron clay.
There is also evidence that individual nucleotides can be created spontaneously. assembled with chain To make RNA. This is an important next step. RNA world hypothesisThis assumes that the first ‘life’ on Earth was a strand of RNA.
A key question is how these RNA molecules could have evolved mechanisms to replicate themselves and organize themselves into protocells. Because all known life forms are surrounded by membranes, most researchers studying the origin of life have assumed that membranes must encapsulate these RNAs.
This requires synthesizing the lipids or fats that make up the membrane. However, the materials needed to create geology likely did not exist on early Earth.
With that discovery RNA can spontaneously form biomolecular condensates.In other words, lipids would not be needed to form protocells. If RNA can condense itself into biomolecular condensates, it becomes much more plausible that living molecules arose from non-living chemicals on Earth.
new treatment
For me and other scientists who study biomolecular condensates, it’s exciting to dream about how these rule-breakers might change our view of how biology works. Condensate is already how we change think about human disease It’s the same as Alzheimer’s disease, Huntington’s disease, and Lou Gehrig’s disease.
To do this, researchers are developing several new approaches. Manipulating condensate for medical purposes It’s like a new drug that can promote or dissolve condensates. Whether this new approach to treating the disease will bear fruit is yet to be determined.
In the long run, I would not be surprised if each biomolecular condensate is eventually assigned a specific function. If this happens, you can bet your high school biology students will either learn more or complain in their introductory biology classes.
Alan AlbigAssociate Professor, Department of Biological Sciences, Boise State University
This article is republished from: conversation Under Creative Commons License. read original article.
