Structural Variability of EspG Chaperones from Mycobacterial ESX-1, ESX-3, and ESX-5 Type VII Secretion Systems.

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 β-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 bindin

SUBMITTER: Tuukkanen AT 

PROVIDER: S-EPMC6331215 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature