Biochemical controls: deeper look at cell division (Introduction)

by David Turell , Saturday, July 06, 2024, 18:06 (140 days ago) @ David Turell

How RNAP clamps onto DNA:

https://www.sciencedaily.com/releases/2024/07/240703183715.htm

"Every living cell transcribes DNA into RNA. This process begins when an enzyme called RNA polymerase (RNAP) clamps onto DNA. Within a few hundred milliseconds, the DNA double helix unwinds to form a node known as the transcription bubble, so that one exposed DNA strand can be copied into a complementary RNA strand.

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"Through this partnership, the team captured complexes forming in the first 100 to 500 milliseconds of RNAP meeting DNA, yielding images of four distinct intermediate complexes in enough detail to enable analysis.

"For the first time, a clear picture of the structural changes and intermediates that form during the initial stages of RNA polymerase binding to DNA snapped into focus. "The technology was extremely important to this experiment," Saecker says. "Without the ability to mix DNA and RNAP quickly and capture an image of it in real-time, these results don't exist."

"Upon examining these images, the team managed to outline a sequence of events showing how RNAP interacts with the DNA strands as they separate, at previously unseen levels of detail. As the DNA unwinds, RNAP gradually grips one of the DNA strands to prevent the double helix from coming back together. Each new interaction causes RNAP to change shape, enabling more protein-DNA connections to form. This includes pushing out one part of a protein that blocks DNA from entering RNAP's active site. A stable transcription bubble is thus formed.

"The team proposes that the rate-limiting step in transcription may be the positioning of the DNA template strand within the active site of the RNAP enzyme. This step involves overcoming significant energy barriers and rearranging several components. Future research will aim to confirm this new hypothesis and explore other steps in transcription.

"'We only looked at the very earliest steps in this study," Mueller says. "Next, we're hoping to look at other complexes, later time points, and additional steps in the transcription cycle.'"

Comment: the molecules act as if they have brains, but they are controlled by electro-magnetic forces at play in the biochemical makeup of the process. Did not evolve by chance. Only design can accomplish this.