PDBsum entry 2ebh

Toxin

PDB id: 2ebh

Contents

Protein chain

711 a.a. *

Ligands

GLC-GLC ×2

Waters ×371

* Residue conservation analysis

PDB id:

2ebh

Name:

Toxin

Title:

Crystal structures reveal a thiol-protease like catalytic triad in thE C-terminal region of pasteurella multocida toxin

Structure:

Dermonecrotic toxin. Chain: x. Fragment: c-terminal region, residues 569-1285. Synonym: dnt, pmt, mitogenic toxin. Engineered: yes. Mutation: yes

Source:

Pasteurella multocida. Organism_taxid: 747. Strain: g-7. Gene: toxa. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

Resolution:

2.40Å R-factor: 0.213 R-free: 0.249

Authors:

K.Kitadokoro,Y.Horiguchi,S.Kamitani

Key ref:

K.Kitadokoro et al. (2007). Crystal structures reveal a thiol protease-like catalytic triad in the C-terminal region of Pasteurella multocida toxin. Proc Natl Acad Sci U S A, 104, 5139-5144. PubMed id: 17360394 DOI: 10.1073/pnas.0608197104

Date:

08-Feb-07 Release date: 06-Mar-07

Protein chain

P17452  (TOXA_PASMD) -  Dermonecrotic toxin from Pasteurella multocida

Seq: 1285 a.a.

Struc: 711 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1073/pnas.0608197104

Proc Natl Acad Sci U S A 104:5139-5144 (2007)

PubMed id: 17360394

Crystal structures reveal a thiol protease-like catalytic triad in the C-terminal region of Pasteurella multocida toxin.

K.Kitadokoro, S.Kamitani, M.Miyazawa, M.Hanajima-Ozawa, A.Fukui, M.Miyake, Y.Horiguchi.

ABSTRACT

Pasteurella multocida toxin (PMT), one of the virulence factors produced by the bacteria, exerts its toxicity by up-regulating various signaling cascades downstream of the heterotrimeric GTPases Gq and G12/13 in an unknown fashion. Here, we present the crystal structure of the C-terminal region (residues 575-1,285) of PMT, which carries an intracellularly active moiety. The overall structure of C-terminal region of PMT displays a Trojan horse-like shape, composed of three domains with a "feet"-,"body"-, and "head"-type arrangement, which were designated C1, C2, and C3 from the N to the C terminus, respectively. The C1 domain, showing marked similarity in steric structure to the N-terminal domain of Clostridium difficile toxin B, was found to lead the toxin molecule to the plasma membrane. The C3 domain possesses the Cys-His-Asp catalytic triad that is organized only when the Cys is released from a disulfide bond. The steric alignment of the triad corresponded well to that of papain or other enzymes carrying Cys-His-Asp. PMT toxicities on target cells were completely abrogated when one of the amino acids constituting the triad was mutated. Our results indicate that PMT is an enzyme toxin carrying the cysteine protease-like catalytic triad dependent on the redox state and functions on the cytoplasmic face of the plasma membrane of target cells.

Selected figure(s)

Figure 4.
Fig. 4. Dynamic alterations in the loop[H28-H29] upon breakage of the disulfide bond. (A–C) The loop[H28-H29] and the proximal regions in C-PMT (A), C-PMT[1159S] (B), and C-PMT[1165S] (C) are shown. A [A]-weighted omit electron density map (contoured at 3 ) is superimposed on the stick model of key residues, Cys^1159 (Ser^1159 in B), Cys^1165 (Ser^1165 in C), His^1205, Asp^1220, and Gln^1225. (D) Comparison of the active sites among C-PMT[1159S] (light green) and C-PMT[1165S] (light blue) with papain (pink), AvrPphB (lime green), and N-acetyltransferase (orange). His^1205, Asp^1220, and Cys^1165 of C-PMT[1159S] were superimposed on the corresponding residues of the counterpart proteins by Lsqkab in the CCP4 program suite (30).

Figure 5.
Fig. 5. Model of the domain architecture of membrane-associated C-PMT. A ribbon diagram of C-PMT[1159S] is presented. The C1, C2, and C3 domains are in blue, green, and magenta, respectively. Note that the membrane-targeting region in the C1 domain (yellow oval) and the catalytic cleft in the C3 domain (red oval) reside on the same face of the molecule, which faces the cytoplasmic surface of the membrane.

Figures were selected by an automated process.