6XXE:
reference: Cryo-electron microscopy reveals two distinct type IV pili assembled by the same bacterium., Neuhaus A, Selvaraj M, Salzer R, Langer JD, Kruse K, Kirchner L, Sanders K, Daum B, Averhoff B, Gold VAM, Nat Commun. 2020 May 6;11(1):2231. doi: 10.1038/s41467-020-15650-w. PMID: 32376942

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