JUN 24, 2017 11:05 AM PDT

Redefining how we Think of the Ribosome

WRITTEN BY: Carmen Leitch

New research is challenging a long-held assumption in molecular biology, and it may also help explain some confounding disorders. Publishing in Molecular Cell, scientists led by Maria Barna at Stanford University have reported that there are differences among the thousands of ribosomes in a cell. They have suggested that ribosomes are tailored to make specific proteins, rather than just acting as generic protein factories, as has long been thought.

 

Ribosomes take up a tremendous amount of cellular power, with cells sometimes giving over 60 percent of their energy to the construction of these organelles, which are made from RNA and 80 various types of proteins. As Jonathan Dinman, a molecular biologist at the University of Maryland in College Park explained, “Life evolved around the ribosome," which synthesize all of the proteins needed by a cell (while proteins go on to carry out the majority of cellular functions).

Although this new work is likely to be debated, "This is really an important step in redefining how we think about this central player in molecular biology," Dinman said. There have also been other reports suggesting that ribosomes are not all the same. 

A mouse that was previously made by this group in 2011 that was deficient in one specific ribosomal protein had a variety of phenotypic abnormalities. The disorders of the mouse suggested that they lacked proteins crucial to development. 

It has been difficult to make real progress in this field with conclusive findings, however. For this work, the scientists used a special technique to determine the levels of various proteins that comprise ribosomes. Of 15 proteins they measured, the levels of nine were equal in the assayed ribosomes, collected from mouse embryonic stem cells. However, there were four proteins not present in 30 - 40 percent of the ribosomes, showing that not all of the ribosomes were the same. Another analysis of 76 ribosomes showed specialization in seven of them.

Structure and shape of the E.coli 70S ribosome. The large 50S ribosomal subunit (red) and small 30S ribosomal subunit (blue) are shown with a 200 Ångstrom (20 nm) scale bar. For the 50S subunit, the 23S (dark red) and 5S (orange red) rRNAs and the ribosomal proteins (pink) are shown. For the 30S subunit, the 16S rRNA (dark blue) and the ribosomal proteins (light blue) are shown. / Credit : Vossman/Wikimedia Commons

Amazingly, the researchers went on to use a technique called ribosome profiling to determine what proteins were being made by these distinctive ribosomes.  Indeed, it seemed the ribosomes did focus on groups of similar proteins. For example, one ribosome made a few proteins that control growth while another synthesized the proteins that enable cells to utilize vitamin B12. The researchers were surprised, Barna said. "I don't think any of us would have expected this."

This intriguing work could help explain some rare diseases called ribosomopathies, in which defective ribosomes cause unusual health problems.  Diamond-Blackfan anemia is one example. The bone marrow that creates new blood cells is dysfunctional, and patients can also present with birth defects.

Barna suggested this may be another way for cells to modulate gene expression, although the reasons why it may be needed are not yet clear.

 

Sources: Science, Molecular Cell

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
AUG 04, 2018
Videos
AUG 04, 2018
A Radical New Approach to Treating Neurodegeneration
The pathways that neural impulses travel can't be retrieved once they're lost... or can they?...
AUG 13, 2018
Microbiology
AUG 13, 2018
Insight Into the Origins of Junk DNA - From Koalas
The human genome isn't only genes. There's also long, repetitive sequences with an unknown function and origin....
AUG 24, 2018
Cell & Molecular Biology
AUG 24, 2018
Chronic Allergies can Change Cells
Chronic rhinosinusitis is different from allergies; it leads to serious inflammation and swelling in the sinuses that can last for years....
AUG 27, 2018
Cell & Molecular Biology
AUG 27, 2018
Stopping Cell Suicide
Chronic inflammation has been linked to many diseases and can trigger cell death....
SEP 03, 2018
Cell & Molecular Biology
SEP 03, 2018
Predicting the Impact of Gene Splicing Errors
Researchers are beginning to learn more about how gene mutations that affect RNA splicing are connected to health problems....
SEP 15, 2018
Microbiology
SEP 15, 2018
Researchers Surprised to Find Bacteria That Make Electricity in the Human Gut
It seems that many microbes, including strains in the human gut that are potentially pathogenic, can generate electricity....
Loading Comments...