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uni'wissen 02-2015_ENG

In a Domain of Their Own In the 1960s and 1970s, researchers dispelled the erroneous belief that these unicellular organ- isms with a penchant for extremes belong to the domain of the bacteria. Scientists classify all living things into domains, also known as empires. Ac- cording to the latest classification, archaea form their own domain – as do bacteria and eukaryotes. The last two contain unicellular organisms with nuclei like yeast cells, as well as plants, fungi, and animals. “On the outside, archaea are hardly distinguishable from bacteria,” says Albers. But there are clear differences in their molecular DNA machinery, which helps them translate genetic information into proteins. In archaea this process does not proceed in the same way as in bacteria, but rather more like in eukaryotes. “Moreover, their metabolism works in a completely different way, and important components of the cell wall indicate that these organisms have a unique status,” the microbiologist stresses. In 1977, the American microbiologist Carl Woese demonstrated that the ribosomal ribonucleic acid (rRNA) of archaea is clearly different from that of bacteria. Ribosomes are cell organelles in which protein biosynthesis occurs with the help of ribo- nucleic acid (RNA). Albers has been studying Sulfolobus acidocal- darius in the lab since 1997. She has even brought this sulfur- and acid-loving archaeon back with her to Freiburg from trips to hot springs at Yellowstone National Park in the USA. Thanks to this archaeon’s preference for hot environ- ments, its proteins are resistant to heat. “We can thus work at room temperature and do without the usual refrigeration,” explains the scientist, who discovered her interest in archaea while writing her degree thesis at the Max Planck Institute of Biochemistry in Martinsried. Her latest findings have led to another unique feature being attrib- uted to the archaea – the way they move. “It had already long been known that archaea can uni wissen 02 2015 The archaeon is surrounded by a protein layer, called the S-layer. It gives the cell a solid shell. The archaellum penetrates the S-layer, and its filament is outside of the cell. The archaellum’s motor, which powers the filament, is located in the cell membrane and consists of the proteins FlaJ, Flal, FlaH, and FlaX. The filament protein itself is called FlaB. FlaF and probably also FlaG serve to anchor the archaellum to the cell wall. Source: Sonja-Verena Albers Hot sulfur vents in the deep sea, so-called black smokers, are home to certain archaea. Photo: P. Rona/NOAA „Von außen sind die Archaeen nur schwer von Bakterien zu unterscheiden“ 30 uni wissen 022015