Neisseria meningitidis Type IV Pili Composed of Sequence Invariable Pilins Are Masked by Multisite Glycosylation

PLoS Pathogens

H. Steven Seifert¹  Michael Nilges²  Guillaume Duménil³  Guillaume Bouvier⁴  Silke Machata⁴  Gérard Péhau-Arnaudet⁴  Christian Malosse⁴  Isabelle Podglajen⁵  Marie Cécile Ploy⁵  Mathias Ferber⁵  Julia Chamot-Rooke⁶  Joseph Gault⁷  Corinne Millien⁷  Arthur Charles-Orszag⁸  Benjamin Bardiaux⁸  Kelly Klinge⁸  Anne-Flore Imhaus⁸ 

[1] CNRS, UMR3528, Paris, France;Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America;INSERM UMR1092, Faculté de Médecine, Université de Limoges, Limoges, France;INSERM, U970, Paris Cardiovascular Research Center, Paris, France;Institut Pasteur, Unité de Bioinformatique Structurale, CNRS UMR 3528, Département de Biologie Structurale et Chimie, Paris, France;Service de Microbiologie, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France;Structural Mass Spectrometry and Proteomics Unit, Institut Pasteur, CNRS UMR 3528, Paris, France;Université Paris Descartes, Faculté de Médecine Paris Descartes, Paris, France

关键词: Glycosylation;    Pili;    fimbriae;    Neisseria meningitidis;    Genetic loci;    Sequence alignment;    Immune system;    DNA sequence analysis;    Pathogen motility;   

DOI  :  10.1371/journal.ppat.1005162

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The ability of pathogens to cause disease depends on their aptitude to escape the immune system. Type IV pili are extracellular filamentous virulence factors composed of pilin monomers and frequently expressed by bacterial pathogens. As such they are major targets for the host immune system. In the human pathogen Neisseria meningitidis, strains expressing class I pilins contain a genetic recombination system that promotes variation of the pilin sequence and is thought to aid immune escape. However, numerous hypervirulent clinical isolates express class II pilins that lack this property. This raises the question of how they evade immunity targeting type IV pili. As glycosylation is a possible source of antigenic variation it was investigated using top-down mass spectrometry to provide the highest molecular precision on the modified proteins. Unlike class I pilins that carry a single glycan, we found that class II pilins display up to 5 glycosylation sites per monomer on the pilus surface. Swapping of pilin class and genetic background shows that the pilin primary structure determines multisite glycosylation while the genetic background determines the nature of the glycans. Absence of glycosylation in class II pilins affects pilus biogenesis or enhances pilus-dependent aggregation in a strain specific fashion highlighting the extensive functional impact of multisite glycosylation. Finally, molecular modeling shows that glycans cover the surface of class II pilins and strongly decrease antibody access to the polypeptide chain. This strongly supports a model where strains expressing class II pilins evade the immune system by changing their sugar structure rather than pilin primary structure. Overall these results show that sequence invariable class II pilins are cloaked in glycans with extensive functional and immunological consequences.

【 授权许可】

CC BY