2d27
From Proteopedia
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'''Structure of the N-terminal domain of XpsE (crystal form I4122)''' | '''Structure of the N-terminal domain of XpsE (crystal form I4122)''' | ||
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[[Category: Huang, C W.]] | [[Category: Huang, C W.]] | ||
[[Category: Shiue, S J.]] | [[Category: Shiue, S J.]] | ||
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| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 23:33:52 2008'' | |
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Revision as of 20:33, 3 May 2008
Structure of the N-terminal domain of XpsE (crystal form I4122)
Overview
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.
About this Structure
2D27 is a Single protein structure of sequence from Xanthomonas campestris. Full crystallographic information is available from OCA.
Reference
Structure and function of the XpsE N-terminal domain, an essential component of the Xanthomonas campestris type II secretion system., Chen Y, Shiue SJ, Huang CW, Chang JL, Chien YL, Hu NT, Chan NL, J Biol Chem. 2005 Dec 23;280(51):42356-63. Epub 2005 Sep 14. PMID:16162504 Page seeded by OCA on Sat May 3 23:33:52 2008
