Archaeal flagellin combines a bacterial type IV pilin domain with an Ig-like domain.
Proc Natl Acad Sci U S A
; 113(37): 10352-7, 2016 09 13.
Article
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| MEDLINE
| ID: mdl-27578865
ABSTRACT
The bacterial flagellar apparatus, which involves â¼40 different proteins, has been a model system for understanding motility and chemotaxis. The bacterial flagellar filament, largely composed of a single protein, flagellin, has been a model for understanding protein assembly. This system has no homology to the eukaryotic flagellum, in which the filament alone, composed of a microtubule-based axoneme, contains more than 400 different proteins. The archaeal flagellar system is simpler still, in some cases having â¼13 different proteins with a single flagellar filament protein. The archaeal flagellar system has no homology to the bacterial one and must have arisen by convergent evolution. However, it has been understood that the N-terminal domain of the archaeal flagellin is a homolog of the N-terminal domain of bacterial type IV pilin, showing once again how proteins can be repurposed in evolution for different functions. Using cryo-EM, we have been able to generate a nearly complete atomic model for a flagellar-like filament of the archaeon Ignicoccus hospitalis from a reconstruction at â¼4-Å resolution. We can now show that the archaeal flagellar filament contains a ß-sandwich, previously seen in the FlaF protein that forms the anchor for the archaeal flagellar filament. In contrast to the bacterial flagellar filament, where the outer globular domains make no contact with each other and are not necessary for either assembly or motility, the archaeal flagellin outer domains make extensive contacts with each other that largely determine the interesting mechanical properties of these filaments, allowing these filaments to flex.
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1
Banco de datos:
MEDLINE
Asunto principal:
Evolución Molecular
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Proteínas Arqueales
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Proteínas Fimbrias
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Flagelina
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2016
Tipo del documento:
Article