title: Structure of EspB, a secreted substrate of the ESX-1 secretion system of Mycobacterium tuberculosis.
abstract: Mycobacterium tuberculosis secretes multiple virulence factors during infection via the general Sec and Tat pathways, and via specialized ESX secretion systems, also referred to as type VII secretion systems. The ESX-1 secretion system is an important virulence determinant because deletion of ESX-1 leads to attenuation of M. tuberculosis. ESX-1 secreted protein B (EspB) contains putative PE (Pro-Glu) and PPE (Pro-Pro-Glu) domains, and a C-terminal domain, which is processed by MycP1 protease during secretion. We determined the crystal structure of PE-PPE domains of EspB, which represents an all-helical, elongated molecule closely resembling the structure of the PE25-PPE41 heterodimer despite limited sequence similarity. Also, we determined the structure of full-length EspB, which does not have interpretable electron density for the C-terminal domain confirming that it is largely disordered. Comparative analysis of EspB in cell lysate and culture filtrates of M. tuberculosis revealed that mature secreted EspB forms oligomers. Electron microscopy analysis showed that the N-terminal fragment of EspB forms donut-shaped particles. These data provide a rationale for the future investigation of EspB's role in M. tuberculosis pathogenesis.
authors.affiliation: Department of Molecular & Cellular Biochemistry, and Center for Structural Biology, University of Kentucky, Lexington, KY, 40536, United States.
authors.forename: Natalia
authors.initials: N
authors.lastname: Korotkova
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Jérémie
authors.initials: J
authors.lastname: Piton
authors.affiliation: Department of Molecular & Cellular Biochemistry, and Center for Structural Biology, University of Kentucky, Lexington, KY, 40536, United States.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Wagner
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Boy-Röttger
authors.affiliation: Laboratory of Physics of Living Matter, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Aleksandre
authors.initials: A
authors.lastname: Japaridze
authors.affiliation: Department of Molecular & Cellular Biochemistry, and Center for Structural Biology, University of Kentucky, Lexington, KY, 40536, United States.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Evans
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Stewart T
authors.initials: ST
authors.lastname: Cole
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland. Electronic address: florence.pojer@epfl.ch.
authors.forename: Florence
authors.initials: F
authors.lastname: Pojer
authors.affiliation: Department of Molecular & Cellular Biochemistry, and Center for Structural Biology, University of Kentucky, Lexington, KY, 40536, United States. Electronic address: kkorotkov@uky.edu.
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Korotkov
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D000069377:Type VII Secretion Systems / Q000737:chemistry*; D037521:Virulence Factors / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; D000069377:Type VII Secretion Systems; D037521:Virulence Factors
keywords: ESX; PE domain; PPE domain; Type VII secretion system