Hot tip for wrapping up genes

 作者:贾充弯     |      日期:2019-02-26 04:10:07
HEAT-LOVING bugs may have taught plants, animals and humans a vital trick for packaging their genes. The single-celled organisms, members of a group known as Archaea, have no cell nucleus, but can live at incredibly high temperatures and pressures. “We were trying to understand how the Archaea keep their DNA together at these high temperatures,” says John Reeve of Ohio State University in Columbus. A few years ago, Reeve’s team discovered a protein in archaeal cells that could hold DNA together even in very hot conditions. The protein turned out to be similar to histones —vital proteins not normally found in bacteria, but present in every cell of every fungus, plant and animal, including humans. In cells with nuclei, histones form spools called nucleosomes around which genes are wound. Without histones, the cells would be unable to squeeze all their DNA into the nucleus. Now Reeve and his colleagues have shown that the archaeal cells also have mini-nucleosomes. Although archaeal nucleosomes contain four, rather than the normal eight histone proteins, they nevertheless seem to create tight bundles of DNA throughout their genome similar to those in nucleated cells (Proceedings of the National Academy of Sciences, vol 94, p 12 633). Since there is fossil evidence that Archaea existed before nucleated cells, Reeve says this might explain the origin of genetic packaging. “It could have started as a glue to hold DNA together,