Researchers at the Institut Pasteur and colleagues in the US have used electron cryo-microscopy to determine the structures of pili on the surface of Sulfolobus islandicus, cells that grow in very harsh environments of pH3 and 80°C. When removed from cells, these pili resist digestion by trypsin or pepsin, and survive boiling in sodium dodecyl sulphate or 5 M guanidine hydrochloride.
Mass measurements also point to extensive glycosylation on the structures, which could be responsible for their remarkable stability. They could have common evolutionary origins with archaeal flagellin, another filamentary structure found in microorganisms.
Read the research paper: An extensively glycosylated archaeal pilus survives extreme conditions, Fengbin Wang et al., Nature Microbiology 10.1038/s41564-019-0458-x