Structural Variability of EspG Chaperones from Mycobacterial ESX-1, ESX-3, and ESX-5 Type VII Secretion Systems.
J Mol Biol
; 431(2): 289-307, 2019 01 18.
Article
em En
| MEDLINE
| ID: mdl-30419243
ABSTRACT
Type VII secretion systems (ESX) are responsible for transport of multiple proteins in mycobacteria. How different ESX systems achieve specific secretion of cognate substrates remains elusive. In the ESX systems, the cytoplasmic chaperone EspG forms complexes with heterodimeric PE-PPE substrates that are secreted from the cells or remain associated with the cell surface. Here we report the crystal structure of the EspG1 chaperone from the ESX-1 system determined using a fusion strategy with T4 lysozyme. EspG1 adopts a quasi 2-fold symmetric structure that consists of a central ß-sheet and two α-helical bundles. In addition, we describe the structures of EspG3 chaperones from four different crystal forms. Alternate conformations of the putative PE-PPE binding site are revealed by comparison of the available EspG3 structures. Analysis of EspG1, EspG3, and EspG5 chaperones using small-angle X-ray scattering reveals that EspG1 and EspG3 chaperones form dimers in solution, which we observed in several of our crystal forms. Finally, we propose a model of the ESX-3 specific EspG3-PE5-PPE4 complex based on the small-angle X-ray scattering analysis.
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Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
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Chaperonas Moleculares
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Fatores de Virulência
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Sistemas de Secreção Tipo VII
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Mycobacterium tuberculosis
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Antígenos de Bactérias
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article