3X3N

Crystal structure of EccB1 of Mycobacterium tuberculosis in spacegroup P21

Summary for 3X3N

• Entry DOI: 10.2210/pdb3x3n/pdb
• Related: 3X3M
• Descriptor: ESX-1 secretion system protein EccB1, CALCIUM ION (3 entities in total)
• Functional Keywords: alpha-beta-alpha sandwich, beta-sheet, atpase, protein transport
• Biological source: Mycobacterium tuberculosis
• Total number of polymer chains: 1
• Total formula weight: 46300.74

Authors

Zhang, X.L.,Li, D.F.,Zhang, X.E.,Bi, L.J.,Wang, D.C. (deposition date: 2015-01-24, release date: 2015-12-09, Last modification date: 2022-08-24)

Primary citation

Zhang, X.L.,Li, D.F.,Fleming, J.,Wang, L.W.,Zhou, Y.,Wang, D.C.,Zhang, X.E.,Bi, L.J.
Core component EccB1 of the Mycobacterium tuberculosis type VII secretion system is a periplasmic ATPase.
Faseb J., 29:4804-4814, 2015

PubMed Abstract: Pathogenic mycobacteria transport virulence factors across their complex cell wall via a type VII secretion system (T7SS)/early secreted antigenic target-6 of kDa secretion system (ESX). ESX conserved component (Ecc) B, a core component of the T7SS architecture, is predicted to be a membrane bound protein, but little is known about its structure and function. Here, we characterize EccB1, showing that it is an ATPase with no sequence or structural homology to other ATPases located in the cell envelope of Mycobacterium tuberculosis H37Rv. We obtained the crystal structure of an EccB1-ΔN72 truncated transmembrane helix and performed modeling and ATP docking studies, showing that EccB1 likely exists as a hexamer. Sequence alignment and ATPase activity determination of EccB1 homologues indicated the presence of 3 conserved motifs in the N- and C-terminals of EccB1-ΔN72 that assemble together between 2 membrane proximal domains of the EccB1-ΔN72 monomer. Models of the EccB1 hexamer show that 2 of the conserved motifs are involved in ATPase activity and form an ATP binding pocket located on the surface of 2 adjacent molecules. Our results suggest that EccB may act as the energy provider in the transport of T7SS virulence factors and may be involved in the formation of a channel across the mycomembrane.

PubMed: 26396239
DOI: 10.1096/fj.15-270843

Experimental method

X-RAY DIFFRACTION (2 Å)