PDBsum entry 2bsh

Chaperone

PDB id: 2bsh

Contents

Protein chains

120 a.a. *

Waters ×139

* Residue conservation analysis

PDB id:

2bsh

Name:

Chaperone

Title:

Crystal structure of the type iii secretion chaperone syct from yersinia enterocolitica (crystal form 2)

Structure:

Syct. Chain: a, b. Engineered: yes

Source:

Yersinia enterocolitica. Organism_taxid: 630. Strain: w22703. Variant: serotype o\:9. Expressed in: escherichia coli. Expression_system_taxid: 469008. Other_details: yersinia enterocolitica virulence plasmid pyve227

Biol. unit:

Dimer (from PDB file)

Resolution:

1.90Å R-factor: 0.176 R-free: 0.220

Authors:

C.R.Buttner,G.R.Cornelis,D.W.Heinz,H.H.Niemann

Key ref:

C.R.Büttner et al. (2005). Crystal structure of Yersinia enterocolitica type III secretion chaperone SycT. Protein Sci, 14, 1993-2002. PubMed id: 16046625 DOI: 10.1110/ps.051474605

Date:

21-May-05 Release date: 15-Aug-05

Protein chains

P0C2V9  (SYCT_YEREN) -  Chaperone protein SycT from Yersinia enterocolitica

Seq: 130 a.a.

Struc: 120 a.a.

DOI no: 10.1110/ps.051474605

Protein Sci 14:1993-2002 (2005)

PubMed id: 16046625

Crystal structure of Yersinia enterocolitica type III secretion chaperone SycT.

C.R.Büttner, G.R.Cornelis, D.W.Heinz, H.H.Niemann.

ABSTRACT

Pathogenic Yersinia species use a type III secretion (TTS) system to deliver a number of cytotoxic effector proteins directly into the mammalian host cell. To ensure effective translocation, several such effector proteins transiently bind to specific chaperones in the bacterial cytoplasm. Correspondingly, SycT is the chaperone of YopT, a cysteine protease that cleaves the membrane-anchor of Rho-GTPases in the host. We have analyzed the complex between YopT and SycT and determined the structure of SycT in three crystal forms. Biochemical studies indicate a stoichometric effector/chaperone ratio of 1:2 and the chaperone-binding site contains at least residues 52-103 of YopT. The crystal structures reveal a SycT homodimer with an overall fold similar to that of other TTS effector chaperones. In contrast to the canonical five-stranded anti-parallel beta-sheet flanked by three alpha-helices, SycT lacks the dimerization alpha-helix and has an additional beta-strand capable of undergoing a conformational change. The dimer interface consists of two beta-strands and the connecting loops. Two hydrophobic patches involved in effector binding in other TTS effector chaperones are also found in SycT. The structural similarity of SycT to other chaperones and the spatial conservation of effector-binding sites support the idea that TTS effector chaperones form a single functional and structural group.

Selected figure(s)

Figure 2.
Figure 2. SycT lacks the dimerization helix 2. Ribbon models of Yersinia enterocolitica SycT, Yersinia pseudotuberculosis SycE (PDB identifier 1L2W [PDB] ; Birtalan et al. 2002), Salmonella typhimurium SicP (1JYO; Stebbins and Galan 2001), Salmonella enterica SigE (1K3S; Luo et al. 2001), Yersinia pestis SycH (1TTW; Phan et al. 2004), Pseudomonas syringae pv. phaseolicola AvrPphF ORF1 (1S28; Singer et al. 2004), and Shigella flexneri Spa15 (1R9Y; Van Eerde et al. 2004). The monomers in a dimer are colored blue and red. The helices 2 are highlighted in orange and turquoise.

Figure 3.
Figure 3. Cavity in the SycT dimerization interface. A polar cavity is enclosed in the dimerization interface of SycT (crystal form #1, cavity as pink surface model and blue side chains of residues Trp47, Pro70, Ala71, His72, Val73, Leu83, Trp84, Ser85, and Ser88, and red side chain for Gln86). Both Val90 residues (green) shield the cavity from the outside. In contrast, the cavity in SycH is accessible and possesses a positive charge (Arg80, red side chain).

The above figures are reprinted by permission from the Protein Society: Protein Sci (2005, 14, 1993-2002) copyright 2005.

Figures were selected by the author.