Genome complexity: controlling plant growth (Introduction)

by David Turell , Thursday, April 28, 2022, 22:10 (940 days ago) @ David Turell

A special enzyme is involved:

https://phys.org/news/2022-04-enzyme-strigolactone-hormone-growth.html

"As sessile organisms, plants have to continually adapt their growth and architecture to the ever-changing environment. To do so, plants have evolved distinct molecular mechanisms to sense and respond to the environment and integrate the signals from outside with endogenous developmental programs.

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"The work stems from a study by Shabek, published in Nature in 2018, unraveling molecular and structural changes in an enzyme, MAX2 (or D3) ubiquitin ligase. MAX2 was found in locked or unlocked forms that can recruit a strigolactone sensor, D14, and target for destruction a DNA transcriptional repressor complex, D53. Ubiquitins are small proteins, found in all eukaryotes, that "tag" other proteins for destruction within a cell.

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"They found that in the unlocked conformation, MAX2 can target the repressor proteins and biochemically decorate them with small ubiquitin proteins, tagging them for destruction. Removing these repressors allows other genes to be expressed—activating a massive gene network that governs shoot branching, root architecture, leaf senescence, and symbiosis with fungi, Shabek said.

"Sending these repressors to the proteasome disposal complexes requires the enzyme to relock again. The team also showed that MAX2 not only targets the repressor proteins, but once it is locked, the strigolactone sensor itself is destroyed, returning the system to its original state.

"Finally, the study uncovered the key to the lock, an organic acid metabolite that can directly trigger the conformational switch."

Comment: Once again, a complex mechanism which involves a giant enzyme molecule o drive the process. Without these specialized molecules, there would be no life. Design is required.