biostudies-literatureGaines MCEC | Horizon 2020 Framework ProgrammeWellcome TrustBiotechnology and Biological Sciences Research Council7411https://www.ebi.ac.uk/biostudies/studies/S-EPMC9715654biostudies-literatureUnknown13(1)Pili are filamentous surface extensions that play roles in bacterial and archaeal cellular processes such as adhesion, biofilm formation, motility, cell-cell communication, DNA uptake and horizontal gene transfer. The model archaeaon Sulfolobus acidocaldarius assembles three filaments of the type-IV pilus superfamily (archaella, archaeal adhesion pili and UV-inducible pili), as well as a so-far uncharacterised fourth filament, named "thread". Here, we report on the cryo-EM structure of the archaeal thread. The filament is highly glycosylated and consists of subunits of the protein Saci_0406, arranged in a head-to-tail manner. Saci_0406 displays structural similarity, but low sequence homology, to bacterial type-I pilins. Thread subunits are interconnected via donor strand complementation, Nature communicationsElectron cryo-microscopy reveals the structure of the archaeal thread filament.PMC9715654803894BB/R008639/1Isupov MNDaum BGold VAMMcLaren MAlbers SVMollat CLHaque RUNeuhaus ASivabalasarma STripp PGaines MCfalseElectron cryo-microscopy reveals the structure of the archaeal thread filament.Pili are filamentous surface extensions that play roles in bacterial and archaeal cellular processes such as adhesion, biofilm formation, motility, cell-cell communication, DNA uptake and horizontal gene transfer. The model archaeaon Sulfolobus acidocaldarius assembles three filaments of the type-IV pilus superfamily (archaella, archaeal adhesion pili and UV-inducible pili), as well as a so-far uncharacterised fourth filament, named "thread". Here, we report on the cryo-EM structure of the archaeal thread. The filament is highly glycosylated and consists of subunits of the protein Saci_0406, arranged in a head-to-tail manner. Saci_0406 displays structural similarity, but low sequence homology, to bacterial type-I pilins. Thread subunits are interconnected via donor strand complementation, 2022-01-01T00:00:00Z2022 Dec2026-05-27T22:55:48.232Z2025-04-06T12:12:14.371ZS-EPMC97156543645654310.1038/s41467-022-34652-4