Cell Biologists Describe a “Beautiful, Flawless Machine”
All life depends on the Kinetochore.
It hasn’t evolved for a “billion years.”
Andrea Musacchio has been trying to understand the kinetochore for 20 years. A research leader at the Max Planck Institute, has been driven by the motto, “Before we understand how things go wrong, we better understand why and how things work.” His team recently built a model of this complex machine that allows them to begin to understand this essential contraption that is at the center of mitosis: eukaryotic cell division.
It´s a cellular process going on since one billion years, yet we are not able to replicate it, nor to fully understand it. Mitosis, the mechanism of cell division that is so important for life, involves more than 100 proteins at its core. Now, the group of Andrea Musacchio from the Max Planck Institute of Molecular Physiology in Dortmund has been able to fully reconstitute the engine of the mitosis machinery, called kinetochore.
How well does the machine work? Here, Musacchio waxes eloquent, as if he has been watching a grand opera in a foreign language. He thinks he can now can understand all the words and see the overall plot, but still is trying to figure out the story details.
As a human cell begins division, its 23 chromosomes duplicate into identical copies that remain joined at a region called the centromere. Here lies the kinetochore, a complicated assembly of proteins that binds to thread-like structures, the microtubules. As mitosis progresses, the kinetochore gives green light to the microtubules to tear the DNA copies apart, towards the new forming cells. “The kinetochore is a beautiful, flawless machine: You almost never lose a chromosome in a normal cell!”, says Musacchio. “We already know the proteins that constitute it, yet important questions about how the kinetochore works are still open: How does it rebuild itself during chromosome replication? How does it bind to the microtubules? And how does it control them?”
Beautiful. Flawless. The kinetochore (from the Greek “motion place”) binds the spindle fibers to the centromere of each chromosome, a spot at the center of a chromosome made for attachment to the spindle. Those who recall the stages of cell division in high school remember that the chromosome pairs all line up in the center of the cell. At metaphase, something “lassos” each sister chromatid (individual member of the pair) at the centromere and exerts force to pull them apart into the daughter cells at anaphase.
The kinetochore is right at the center of this action, binding to both the centromere and the microtubules in the spindle. It is therefore not only a machine able to contact each chromosome’s centromere; it is also a traffic cop. It will not let cell division proceed until it gives the green light.
What about that billion years?
“This is a real milestone in the reconstruction of an object that exists, unaltered, in all eukaryotic cells since more than one billion years!”, says Musacchio.
Musacchio did not watch the billion years onstage, of course. It’s just a statement in the program notes written by a Darwin propagandist describing what must have happened before the show started. Natural selection can turn a small four-legged mammal into a whale in 0.7% of that time, he wrote, but sometimes evolution just stays the same. Evolution often does that (see Living Fossils, 29 July 2021). Stasis (non-evolution) is a consequence of the Stuff Happens Law. Sometimes nothing happens.
“The kinetochore is a beautiful, flawless machine: You almost never lose a chromosome in a normal cell!” -Max Planck Institute
What the Max Planck team actually saw was not a random, purposeless process on stage. They saw a beautiful, flawless machine that works perfectly almost all the time. Kinetochores are pulling chromosomes apart into daughter cells every day, in every eukaryotic organism, all over the world. How many quadrillions of times has this occurred without an evolutionary upgrade?
Musacchio’s team has been able to imitate the performance with homemade proteins. When they assemble their “Lego pieces” in a dish, they snap together like a kinetochore. Next, the team wants to see what their imitation machines do when given ATP for energy. Will they be able to pull on microtubules? Will they know when to play ‘red light, green light’?
Lead author Kai Walstein is shown in the press release. The work was published in the AAAS open-access journal Science Advances.
Walstein et al., “Assembly principles and stoichiometry of a complete human kinetochore module,” Science Advances 30 Jun 2021: Vol. 7, no. 27, eabg1037, DOI: 10.1126/sciadv.abg1037.
Details on some of the hundred proteins and what they bind to are described in the paper. Oddly, there is no mention of evolution, natural selection, or a billion years. Apparently those concepts did not contribute anything useful to understanding “how and why things work.”
Remember Paul Nelson’s father’s comment? “If something works, it’s not happening by accident.”
The kinetochore is astonishingly complex, a wonder to behold. Before cell division begins, though, recall that the entire genome is duplicated inside the nucleus. A host of molecular machines travel down each DNA strand, copying every letter and proofreading the copy to a high degree of accuracy — all while the cell is still operating. There are checkpoints all along the way: signals indicating “go/no-go” decisions, just like used in the space program.
Then the copies are arranged into chromosomes that compact the code into highly-organized bundles with centromeres at each chromosome’s “center of gravity” (so to speak) so that the pulling force will operate safely without tearing the chromosome apart. The nuclear membrane disintegrates and the chromosomes arrange themselves in pairs along the center. The kinetochores do their beautiful, flawless work. Then additional machines tighten a loop around the membrane, like a drawstring, that separates the two daughter cells in a process called cytokinesis (cell motion). See our ranch analogy in the 28 Dec 2007 and 4 March 2004 articles.
This is all so perfect, so amazing, so well designed, it should send Darwin screaming for the hills. He knew nothing of this! We have to get the Darwin Party to fess up to the reality of modern cell biology and stop pretending that “stuff happens” explains it. This is intelligent engineering at its finest. It is far beyond anything humans have ever designed. Give glory to the Designer who made cells, life, and brains to comprehend his works. “Let all the earth fear the Lord; let all the inhabitants of the world stand in awe of him!” (Psalm 33:8)
Courtesy Illustra Media, the John 10:10 Project.