PDBsum entry 1xkp

Membrane protein/chaperon

PDB id: 1xkp

Contents

Protein chains

231 a.a. *

121 a.a. *

126 a.a. *

Waters ×179

* Residue conservation analysis

PDB id:

1xkp

Name:

Membrane protein/chaperon

Title:

Crystal structure of the virulence factor yopn in complex with its heterodimeric chaperone sycn-yscb

Structure:

Putative membrane-bound yop targeting protein yopn. Chain: a. Fragment: residues 32-277. Engineered: yes. Mutation: yes. Chaperone protein sycn. Chain: b. Engineered: yes. Mutation: yes.

Source:

Yersinia pestis. Organism_taxid: 632. Gene: yopn. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693. Gene: sycn. Gene: yscb.

Biol. unit:

Trimer (from PQS)

Resolution:

1.70Å R-factor: 0.201 R-free: 0.242

Authors:

F.D.Schubot,M.W.Jackson,K.J.Penrose,S.Cherry,J.E.Tropea,G.V.Plano, D.S.Waugh

Key ref:

F.D.Schubot et al. (2005). Three-dimensional structure of a macromolecular assembly that regulates type III secretion in Yersinia pestis. J Mol Biol, 346, 1147-1161. PubMed id: 15701523 DOI: 10.1016/j.jmb.2004.12.036

Date:

29-Sep-04 Release date: 22-Mar-05

Protein chain

P68640  (YOPN_YERPE) -  Outer membrane protein YopN from Yersinia pestis

Seq: 293 a.a.

Struc: 231 a.a.*

Protein chain

P61380  (SYCN_YERPE) -  Chaperone protein SycN from Yersinia pestis

Seq: 123 a.a.

Struc: 121 a.a.*

Protein chain

Q56973  (YSCB_YERPE) -  Chaperone protein YscB from Yersinia pestis

Seq: 137 a.a.

Struc: 126 a.a.*

* PDB and UniProt seqs differ at 21 residue positions (black crosses)

DOI no: 10.1016/j.jmb.2004.12.036

J Mol Biol 346:1147-1161 (2005)

PubMed id: 15701523

Three-dimensional structure of a macromolecular assembly that regulates type III secretion in Yersinia pestis.

F.D.Schubot, M.W.Jackson, K.J.Penrose, S.Cherry, J.E.Tropea, G.V.Plano, D.S.Waugh.

ABSTRACT

Yersinia pestis, the causative agent of plague, utilizes a type III secretion system (T3SS) to inject effector proteins directly into the cytosol of mammalian cells where they interfere with signal transduction pathways that regulate actin cytoskeleton dynamics and inflammation, thereby enabling the bacterium to avoid engulfment and destruction by macrophages. Type III secretion normally does not occur in the absence of close contact with eukaryotic cells. Negative regulation is mediated in part by a multiprotein complex that has been proposed to act as a physical impediment to type III secretion by blocking the entrance to the secretion apparatus prior to contact with mammalian cells. This complex is composed of YopN, its heterodimeric secretion chaperone SycN-YscB, and TyeA. Here, we report two crystal structures of YopN in complex with its heterodimeric secretion chaperone SycN-YscB and the co-regulatory protein TyeA, respectively. By merging these two overlapping structures, it was possible to construct a credible theoretical model of the YopN-SycN-YscB-TyeA complex. The modeled assembly features the secretion signaling elements of YopN at one end of an elongated structure and the secretion regulating TyeA binding site at the other. A patch of highly conserved residues on the surface of the C-terminal alpha-helix of TyeA may mediate its interaction with structural components of the secretion apparatus. Conserved arginine residues that reside inside a prominent cavity at the dimer interface of SycN-YscB were mutated in order to investigate whether they play a role in targeting the YopN-chaperone complex to the type III secretion apparatus. One of the mutants exhibited a phenotype that is consistent with this hypothesis.

Selected figure(s)

Figure 1.
Figure 1. (a) Two orthogonal views showing the ribbon model of the ternary complex between YopN and its heterodimeric secretion chaperone SycN–YscB. YopN, SycN and YscB are represented in cyan, orange and yellow, respectively. The broken line between YopN residues Thr57 and Glu65 denotes the disordered region of the CBD. This Figure was generated by PYMOL^51 (http://www.pymol.org). (b) Structure of the YopN^76-293–TyeA complex. YopN and TyeA are depicted in cyan and red, respectively. Helices α-1 and α-3 of TyeA surround helix α-12 of YopN to form the bulk of the intermolecular interface.

Figure 6.
Figure 6. A model of the YopN–SycN–YscB–TyeA complex constructed by merging the two overlapping crystal structures. The RMSD of only 1 Å between the YopN molecules in the two structures allowed the construction of the model, which in all likelihood depicts the assembly as it exists in the Y. pestis cytoplasm. Noteworthy are the seeming rigidity of the structure and the spatial separation of secretion targeting and secretion regulating elements.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2005, 346, 1147-1161) copyright 2005.

Figures were selected by an automated process.