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
May 2025 ICR Wallpaper
"Now may the God of hope fill you with all joy and peace in believing, that you may abound in hope by the power of the Holy Spirit." (Romans...

NEWS
Acoustic Communication in Animals
We are all familiar with vocalizations in the animal world. For example, dogs bark, birds sing, frogs croak, and whales send forth their own distinct...

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

APOLOGETICS
Playing Chess with Little Furry Critters
God’s multifarious and marvelous designs for basic creature needs are so innovatively clever and providentially purposeful that Christ’s...

ACTS & FACTS
Credit Only Our Creator
History was my favorite subject as a young kid. But it always puzzled me when my teachers said, “We study history so that we don’t repeat...

ACTS & FACTS
Genomic Tandem Repeats: Where Repetition Is Purposely Adaptive
Tandem repeats (TRs) are short sequences of DNA repeated over and over again like the DNA letter sequence TACTACTAC, which is a repetition of TAC three...

ACTS & FACTS
Dinosaur National Monument: Fossil Graveyard of the Flood
Straddling the border of Utah and Colorado, Dinosaur National Monument (DNM) is one of the richest exposures of dinosaur fossils in the world.1...

ACTS & FACTS
The Transforming Influence of Genesis: Worker Dignity and Safety
When Pharisees questioned the Lord Jesus about marriage, He answered by quoting Genesis 1:27: “But from the beginning of the creation, God ‘made...

NEWS
Giant ''Meg'' Shark: Longer and Leaner?
Fossil remains of the giant shark Otodus megalodon have been found in Miocene1 and Pliocene2 rock layers, which ICR scientists...

CREATION.LIVE PODCAST
Searching for Truth Across the Globe | Creation.Live Podcast:...
How can we bring the Gospel of Jesus Christ and the truth of creation to others outside our small spheres of influence?   Host...