Genome complexity: transcription controls are tight (Introduction)

by David Turell , Monday, September 06, 2021, 18:00 (963 days ago) @ David Turell

An other study:

https://phys.org/news/2021-09-transcription-elongation-checkpoint.html

"According to the study, the presence of a protein called SPT5 serves as a "passport," determining whether a polymerase complex is allowed to proceed down the length of DNA or is instead degraded and destroyed.

"Only RNA Polymerase IIs with SPT5 are allowed to leave the station," said Ali Shilatifard, Ph.D., the Robert Francis Furchgott Professor, chair of Biochemistry and Molecular Genetics and senior author of the study.

***

"During transcription elongation, the RNA polymerase II complex "walks" along one strand of DNA, copying genetic elements to a strand of RNA. Shilatifard's laboratory has previously discovered pauses in this process linked to regulatory checkpoints. Now, using this new method of gene deletion, they've discovered a crucial checkpoint before elongation even starts.

"In cells with SPT5 depleted, polymerase never begin its journey down the strand of DNA. Instead, it is recognized as faulty and degraded. How exactly it is recognized remains unknown, but it's clear that SPT5 serves as a badge of approval, according to Yuki Aoi, Ph.D., a postdoctoral fellow in the Shilatifard laboratory and lead author of the study.

"'If there are issues here, and the polymerase is allowed to go, there could be more issues down the line," Aoi said. "It's only allowing polymerases that are certified to leave because they have SPT5."

"The investigators also discovered that a protein called CUL3 is part of the pathway that destroys polymerases lacking SPT5."

Comment: More evidence for design. This system cannot arise by stepwise additions. It must be complete at its start. Think of it this way: only a complete organ system can work and therefore be judged by natural selection. An incomplete or partial system isn't working and cannot be evaluated.