2D27

Structure of the N-terminal domain of XpsE (crystal form I4122)

Summary for 2D27

• Entry DOI: 10.2210/pdb2d27/pdb
• Related: 2D28
• Descriptor: type II secretion ATPase XpsE (2 entities in total)
• Functional Keywords: alpha-beta sandwich, protein transport
• Biological source: Xanthomonas campestris
• Cellular location: Cytoplasm (Probable): P31742
• Total number of polymer chains: 1
• Total formula weight: 16958.00

Authors

Chen, Y.,Shiue, S.-J.,Huang, C.-W.,Chang, J.-L.,Chien, Y.-L.,Hu, N.-T.,Chan, N.-L. (deposition date: 2005-09-03, release date: 2005-09-20, Last modification date: 2024-11-06)

Primary citation

Chen, Y.,Shiue, S.-J.,Huang, C.-W.,Chang, J.-L.,Chien, Y.-L.,Hu, N.-T.,Chan, N.-L.
Structure and Function of the XpsE N-Terminal Domain, an Essential Component of the Xanthomonas campestris Type II Secretion System
J.Biol.Chem., 280:42356-42363, 2005

PubMed Abstract: Secretion of fully folded extracellular proteins across the outer membrane of Gram-negative bacteria is mainly assisted by the ATP-dependent type II secretion system (T2SS). Depending on species, 12-15 proteins are usually required for the function of T2SS by forming a trans-envelope multiprotein secretion complex. Here we report crystal structures of an essential component of the Xanthomonas campestris T2SS, the 21-kDa N-terminal domain of cytosolic secretion ATPase XpsE (XpsEN), in two conformational states. By mediating interaction between XpsE and the cytoplasmic membrane protein XpsL, XpsEN anchors XpsE to the membrane-associated secretion complex to allow the coupling between ATP utilization and exoprotein secretion. The structure of XpsEN observed in crystal form P4(3)2(1)2 is composed of a 90-residue alpha/beta sandwich core domain capped by a 62-residue N-terminal helical region. The core domain exhibits structural similarity with the NifU-like domain, suggesting that XpsE(N) may be involved in the regulation of XpsE ATPase activity. Surprisingly, although a similar core domain structure was observed in crystal form I4(1)22, the N-terminal 36 residues of the helical region undergo a large structural rearrangement. Deletion analysis indicates that these residues are required for exoprotein secretion by mediating the XpsE/XpsL interaction. Site-directed mutagenesis study further suggests the more compact conformation observed in the P4(3)2(1)2 crystal likely represents the XpsL binding-competent state. Based on these findings, we speculate that XpsE might function in T2SS by cycling between two conformational states. As a closely related protein to XpsE, secretion ATPase PilB may function similarly in the type IV pilus assembly.

PubMed: 16162504
DOI: 10.1074/jbc.M506843200

Experimental method

X-RAY DIFFRACTION (2.21 Å)