Complexity of Cell's 'Molecular Shredder' Revealed | The Institute for Creation Research

Complexity of Cell's 'Molecular Shredder' Revealed

When genes in the cell are turned on, the result is the production of gene copies called messenger RNAs, or mRNAs. The mRNAs are then used as templates to make proteins, the key molecules that enable the cell to function. But what happens to the excess mRNAs when they are no longer needed or the RNAs that have errors in them? They certainly can't remain active in the cell or serious problems would ensue.

A good analogy for the cell's solution to this problem is the example of a common office and household machine. When we have sensitive documents around that are no longer needed, we use a handy specialized machine called a 'paper shredder' to effectively eliminate the documents and the information they contain so it doesn't fall into the wrong hands. In the cell, a similar, but a far more complex machine has recently been characterized and described in a new publication in the journal Nature.1

When mRNAs are no longer needed in the cell, complex molecular machines called exosomes are recruited to "shred" them into basic molecules that can then be recycled. The process is considerably more complex than the example of a human sliding a piece of paper into an office shredder. When mRNAs or other types of RNAs are no longer needed in the cell, they are targeted and tagged with other specialized RNAs. When they are first formed, RNA molecules are single-stranded, but when they get tagged for destruction, they become double-stranded. It is these double-stranded RNAs that are recognized by the exosome. Amazingly, the exosome is multi-purpose in function: it not only shreds the unwanted RNAs, it also processes other RNAs—ones that still need to be utilized in the cell—by performing precision trimming operations.

The exosome itself, is a large complex of specifically arranged protein subunits that have been pieced together by other complicated cell machinery to make a complex, multi-function precision machine. While scientists understood the various proteins involved in the construction of the exosome, they did not fully understand how it worked. Using advanced microscopy techniques, researchers have obtained an atomic-level resolution picture of the exosome caught in the act of processing an RNA molecule.

In an interview, the lead author of the study stated, "It is quite an elaborate machine: the exosome complex forms a hollow barrel formed by nine different proteins through which RNA molecules are threaded to reach a tenth protein, the catalytic subunit, that then shreds the RNA into pieces."2 Not only is the exosome very elaborate in its structure, but it exhibits a common bio-engineering theme called irreducible complexity—meaning that all the parts are required all at once for it to function. The lead author of the study highlights this feature by stating, "Cells lacking any of the ten proteins do not survive and this shows that not only the catalytic subunit but also the entire barrel is critical for the function of the exosome."2

Much is yet to be learned about this amazing cell machine such as how the exosome is selectively targeted by the RNAs tagged for degradation, and how it functions and is regulated in different compartments within the cell.

In addition to refuting random evolutionary processes for its existence, the complex exosome molecular machine shows every sign of carefully crafted system engineering.

References

  1. Makino, D. L. et al. 2013. Crystal structure of an RNA-bound 11-subunit eukaryotic exosome complex. Nature. 495 (7439): 70-75.
  2. Max Planck Institute of Biochemistry. 2013. Researchers unravel the structure of the machinery for RNA disposalScienceDaily. Posted on www.sciencedaily.com March 7, 2012, accessed March 12, 2013.

*Dr. Tomkins is Research Associate at the Institute for Creation Research and received his Ph.D. in Genetics from Clemson University.

Article posted on March 25, 2013.

The Latest
NEWS
Amazing Defense Systems
Bacteria (prokaryotes) are ubiquitous. A fraction cause disease in people, animals, and plants, but the majority are the foundation for the global food...

NEWS
Octopus and Fish Plan a Complex Coordinated Hunt
The octopus—an invertebrate—never fails to surprise researchers with its incredible abilities.1,2 The octopus was designed...

NEWS
A ''40 million year old'' 100% European Gnat
Finding well-preserved creatures in amber1 is a landfall for creation scientists, much like the numerous discoveries of soft dinosaur tissue...

CREATION PODCAST
The Undeniable Power of Narrative | The Creation Podcast: Episode...
Science is objective. At least, that’s what we’re told. But there are inherent issues with this statement that can cause...

NEWS
Paintbrush of the Creator
Who doesn’t enjoy the amazing color patterns of butterflies?1,2 Such beautiful designs and construction do not reflect blind naturalistic...

NEWS
November 2024 ICR Wallpaper
"Rejoice always, pray without ceasing, in everything give thanks; for this is the will of God in Christ Jesus for you." (1 Thessalonians 5:16-18 NKJV) ICR...

NEWS
Reformation Day, October 31
Five hundred years ago in Wittenberg, Germany, an unusual scholar changed the course of human history using pen and hammer. Dr. Martin Luther protested...

ACTS & FACTS
Creation Kids: Owls
by Sydney Walters and Susan Windsor* You're never too young to be a creation scientist and explore our Creator's world. Kids, discover...

ACTS & FACTS
RNA Hoops: When Circular Reasoning Makes Sense
If the regulatory picture of the genome were not complicated enough, over the past decade scientists have discovered another level of Darwinian-defying...

ACTS & FACTS
Gunnison National Forest: Adaptable Aspens and Warped Rocks
Gunnison National Forest’s 1.67-millionplus acres showcase stunning views of the Colorado Rocky Mountains. The Continental Divide forms its eastern...