Filaments from Ignicoccus hospitalis Show Diversity of Packing in Proteins Containing N-Terminal Type IV Pilin Helices

JOURNAL OF MOLECULAR BIOLOGY

卷:422

Article

Yu, Xiong¹  Goforth, Charles¹  Meyer, Carolin²  Rachel, Reinhard²  Wirth, Reinhard²  Schroeder, Gunnar F.³  Egelman, Edward H.¹ 

[1] Univ Virginia, Dept Biochem & Mol Genet, Charlottesville, VA 22908 USA

[2] Univ Regensburg, Archaea Ctr, Dept Microbiol, D-93053 Regensburg, Germany

[3] Forschungszentrum Julich, Inst Complex Syst ICS 6, D-52425 Julich, Germany

关键词: electron microscopy;    helical polymers;    convergent evolution;    archaea;   

DOI  :  10.1016/j.jmb.2012.05.031

来源: Elsevier

【 摘 要 】

Bacterial motility is driven by the rotation of flagellar filaments that supercoil. The supercoiling involves the switching of coiled-coil protofilaments between two different states. In archaea, the flagellar filaments responsible for motility are formed by proteins with distinct homology in their N-terminal portion to bacterial Type IV pilins. The bacterial pilins have a single N-terminal hydrophobic alpha-helix, not the coiled coil found in flagellin. We have used electron cryo-microscopy to study the adhesion filaments from the archaeon Ignicoccus hospitalis. While I. hospitalis is non-motile, these filaments make transitions between rigid stretches and curved regions and appear morphologically similar to true archaeal flagellar filaments. A resolution of similar to 7.5 angstrom allows us to unambiguously build a model for the packing of these N-terminal alpha-helices, and this packing is different from several bacterial Type IV pill whose structure has been analyzed by electron microscopy and modeling. Our results show that the mechanism responsible for the supercoiling of bacterial flagellar filaments cannot apply to archaeal filaments. (C) 2012 Elsevier Ltd. All rights reserved.

【 授权许可】

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