Genome complexity: Archaea and nuclei (Introduction)

by David Turell , Wednesday, November 08, 2017, 17:32 (2573 days ago) @ David Turell

Eukaryotes have nuclei requiring packing proteins to handle long DNA. Related proteins are found in Archaea:

https://phys.org/news/2017-11-human-cells-hardy-microbes-common.html

"Santangelo, associate professor in the Department of Biochemistry and Molecular Biology, was on a team that found striking parallels between how archaeal cells and more complex cells, including humans' and animals', package and store their genetic material. The breakthrough study, published in Science earlier this year, provided evidence that archaea and eukaryotic cells share a common mechanism to compact, organize and structure their genomes.

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"Science paper collaborator John Reeve had discovered in the 1990s that histone proteins were not limited to eukaryotes, but were also found in nucleus-free archaea cells. Reeves and Luger began a collaboration to crystallize histone-based archaeal chromatin and compare that structure with eukaryotic chromatin.

"After years of stops and starts and trouble growing reliable archaeal histone crystals – Luger called it a "gnarly crystallographic problem" – the scientists succeeded in resolving the structure of archaeal chromatin, revealing its structural similarity to eukaryotes.

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"A little high school biology review: Eukaryotes are cells with a nucleus and membrane-bound organelles, and they include fungal, plant and animal – including human – cells. They're set apart from their less complex counterparts, prokaryotes, by the absence of a nucleus. While archaea and bacteria are both prokaryotes, they are only distantly related. Archaea are the likely progenitors of eukaryotes and share many of the same proteins that control gene expression.

"One of life's most fundamental processes – the mechanics by which DNA bends, folds and crams itself into a cell nucleus – is common across all eukaryotes, from microscopic protists to plants to humans.

"Packed inside the nucleus of every eukaryotic cell is several feet of genetic material that is compacted in a very specific way. Small sections of DNA are wrapped, like thread around a spool, roughly two times around eight small proteins called histones. This entire DNA-histone complex is called a nucleosome, and a string of compacted nucleosomes is called chromatin."

Comment: More evidence for pre-planning the future of evolution, just like a change in monkey lumbar changes.

Read more at: https://phys.org/news/2017-11-human-cells-hardy-microbes-common.html#jCp