The secret role histones play in complex cell evolution

For this To Tobias Warne, Who studies archaeological histones at Imperial College London, thinks that “there must have been some special phenomenon in the early days of eukaryotes, where we could simply move from having normal histones … to move the optometric nucleosomes. And they seem to be something qualitatively different.”

Which is still a mystery to archaeological species, “there are several that contain histone, and there are other species that do not have histone. There are many differences even among those who have histone,” Warnek said. Last December he published a paper to be present there Different forms of histone protein With various functions. Histone-DNA complexes vary in their stability and proximity to DNA. However, they are not as stable or regular as eukaryotic nucleosomes.

As amazing as the diversity of Archiel histones is, it also provides an opportunity to understand the various possible ways in which gene expression systems are created. Worker says: We cannot collect anything from the relative “annoyance” of eukaryotes, Warneck says: By understanding the combination of archeological systems, “we can understand what is special about eukaryotic systems.” Different types of histones and different configurations can help us reduce what they were doing before strengthening their role in gene control.

A defensive role for history

“I don’t think the main role of histones was to control gene expression, or at least not the way we were accustomed to eukaryotes,” Warke said. Instead, he speculates that histones may protect the genome from damage.

Archaea often live in extreme environments such as hot springs and volcanic marshes at the bottom of the ocean, characterized by high temperatures, high pressure, high salinity, high acidity or other threats. Stabilizing their DNA with histones can make the DNA strands more difficult to melt in these extreme conditions. While histones can protect archaea against invaders such as phage or transposable elements, it is more difficult to integrate into the genome when it is involved around a protein.

The Kurds agree. “If you were studying Archie 2 billion years ago, genome compaction and gene control is not the first thing you keep in mind when thinking about histones,” he said. In fact, he speculated about a different kind of chemical protection that might have been offered by archaeologists.

Last JulyIn the yeast nucleosomes, two histones have a catalytic site at the interface of the H3 protein that binds the copper and can be electrochemically degraded, the Kurdistan team reported. To unravel its evolutionary significance, the massive increase in oxygen in the Kurdish world, the Great Oxidation Event, which occurred during the first evolution of eukaryotes about 2 billion years ago, must have caused global oxidation of metals such as copper and iron. Although it is excessively toxic). Once oxidized, the metals were less available to the cells, so any cell that kept the metals in reduced form had an advantage.

During the grade oxidation event, the ability to reduce copper would have been “an extremely valuable product,” Kurdistani said. Copper is required for.

Since archaea live in extreme environments, they can find ways to make and handle reduced copper without being killed long before the Great Oxidation event. If so, proto-mitochondria can attack interfering hosts to steal their depleted copper.

Sayavash Kurdistani, a biochemist from Los Angeles, California, speculates on how the catalytic efficiency of some histones supported the endosambiosis of eukaryotes.Photograph: Reed Hutchinson / UCLA Broad Stem Cell Research Center

The hypothesis is interesting because it could explain why eukaryotes appeared when the level of oxygen in the atmosphere increased. “Before that there was a life of 1.5 million years, and there is no sign of eukaryotes,” Kurdistani said. “So the idea that oxygen formed the first eukaryotic cell should, to me, be centered around a hypothesis that tries to come up with why these features were developed.”

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