BILBO1 Is a Scaffold Protein of the Flagellar Pocket Collar in the Pathogen Trypanosoma brucei

PLoS Pathogens

Denis Dacheux¹  Gang Dong¹  Annelise Sahin¹  Mélanie Bonhivers¹  Nicolas Landrein²  Anna Albisetti²  Keni Vidilaseris³  Célia Florimond³  Edward H. Byard³  Derrick R. Robinson³ 

[1] CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France;Max F. Perutz Laboratories, Medical University of Vienna, Vienna, Austria;University Bordeaux, Microbiologie Fondamentale et Pathogenicité, Bordeaux, France

关键词: Polymers;    Trypanosoma;    Flagella;    Cytoskeleton;    Trypanosoma brucei gambiense;    Immunofluorescence;    Phenotypes;    Protein expression;   

DOI  :  10.1371/journal.ppat.1004654

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The flagellar pocket (FP) of the pathogen Trypanosoma brucei is an important single copy structure that is formed by the invagination of the pellicular membrane. It is the unique site of endo- and exocytosis and is required for parasite pathogenicity. The FP consists of distinct structural sub-domains with the least explored being the annulus/horseshoe shaped flagellar pocket collar (FPC). To date the only known component of the FPC is the protein BILBO1, a cytoskeleton protein that has a N-terminus that contains an ubiquitin-like fold, two EF-hand domains, plus a large C-terminal coiled-coil domain. BILBO1 has been shown to bind calcium, but in this work we demonstrate that mutating either or both calcium-binding domains prevents calcium binding. The expression of deletion or mutated forms of BILBO1 in trypanosomes and mammalian cells demonstrate that the coiled-coil domain is necessary and sufficient for the formation of BILBO1 polymers. This is supported by Yeast two-hybrid analysis. Expression of full-length BILBO1 in mammalian cells induces the formation of linear polymers with comma and globular shaped termini, whereas mutation of the canonical calcium-binding domain resulted in the formation of helical polymers and mutation in both EF-hand domains prevented the formation of linear polymers. We also demonstrate that in T. brucei the coiled-coil domain is able to target BILBO1 to the FPC and to form polymers whilst the EF-hand domains influence polymers shape. This data indicates that BILBO1 has intrinsic polymer forming properties and that binding calcium can modulate the form of these polymers. We discuss whether these properties can influence the formation of the FPC.

【 授权许可】

CC BY