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The structure of the endogenous ESX-3 secretion system.

ABSTRACT: The ESX (or Type VII) secretion systems are protein export systems in mycobacteria and many Gram-positive bacteria that mediate a broad range of functions including virulence, conjugation, and metabolic regulation. These systems translocate folded dimers of WXG100-superfamily protein substrates across the cytoplasmic membrane. We report the cryo-electron microscopy structure of an ESX-3 system, purified using an epitope tag inserted with recombineering into the chromosome of the model organism Mycobacterium smegmatis. The structure reveals a stacked architecture that extends above and below the inner membrane of the bacterium. The ESX-3 protomer complex is assembled from a single copy of the EccB3, EccC3, and EccE3 and two copies of the EccD3 protein. In the structure, the protomers form a stable dimer that is consistent with assembly into a larger oligomer. The ESX-3 structure provides a framework for further study of these important bacterial transporters.

SUBMITTER: Poweleit N

PROVIDER: S-EPMC6986878 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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The structure of the endogenous ESX-3 secretion system.

Poweleit Nicole N Czudnochowski Nadine N Nakagawa Rachel R Trinidad Donovan D DD Murphy Kenan C KC Sassetti Christopher M CM Rosenberg Oren S OS

eLife 20191230

The ESX (or Type VII) secretion systems are protein export systems in mycobacteria and many Gram-positive bacteria that mediate a broad range of functions including virulence, conjugation, and metabolic regulation. These systems translocate folded dimers of WXG100-superfamily protein substrates across the cytoplasmic membrane. We report the cryo-electron microscopy structure of an ESX-3 system, purified using an epitope tag inserted with recombineering into the chromosome of the model organism < ...[more]

PMID: 31886769

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