PDBsum entry 2v6l

Protein transport

PDB id: 2v6l

Contents

Protein chains

(+ 22 more) 82 a.a.* *

* Residue conservation analysis

* C-alpha coords only

PDB id:

2v6l

Name:

Protein transport

Title:

Molecular model of a type iii secretion system needle

Structure:

Mxih. Chain: 0, 1, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z. Engineered: yes. Other_details: residues 2-19 were modelled as an alpha helix. Residues 20-80 come from molecule a of PDB entry 2ca5 residues 81-85 were modelled as an alpha helix.

Source:

Shigella flexneri. Organism_taxid: 623. Strain: pwr100. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Authors:

J.E.Deane,P.Roversi,F.S.Cordes,S.Johnson,R.Kenjale,S.Daniell,F.Booy, W.L.Picking,W.D.Picking,A.J.Blocker,S.M.Lea

Key ref:

J.E.Deane et al. (2006). Molecular model of a type III secretion system needle: Implications for host-cell sensing. Proc Natl Acad Sci U S A, 103, 12529-12533. PubMed id: 16888041 DOI: 10.1073/pnas.0602689103

Date:

19-Jul-07 Release date: 31-Jul-07

Protein chains

P0A223  (MXIH_SHIFL) -  Type 3 secretion system needle filament protein from Shigella flexneri

Seq: 83 a.a.

Struc: 82 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1073/pnas.0602689103

Proc Natl Acad Sci U S A 103:12529-12533 (2006)

PubMed id: 16888041

Molecular model of a type III secretion system needle: Implications for host-cell sensing.

J.E.Deane, P.Roversi, F.S.Cordes, S.Johnson, R.Kenjale, S.Daniell, F.Booy, W.D.Picking, W.L.Picking, A.J.Blocker, S.M.Lea.

ABSTRACT

Type III secretion systems are essential virulence determinants for many Gram-negative bacterial pathogens. The type III secretion system consists of cytoplasmic, transmembrane, and extracellular domains. The extracellular domain is a hollow needle protruding above the bacterial surface and is held within a basal body that traverses both bacterial membranes. Effector proteins are translocated, via this external needle, directly into host cells, where they subvert normal cell functions to aid infection. Physical contact with host cells initiates secretion and leads to formation of a pore, thought to be contiguous with the needle channel, in the host-cell membrane. Here, we report the crystal structure of the Shigella flexneri needle subunit MxiH and a complete model for the needle assembly built into our three-dimensional EM reconstruction. The model, combined with mutagenesis data, reveals that signaling of host-cell contact is relayed through the needle via intersubunit contacts and suggests a mode of binding for a tip complex.

Selected figure(s)

Figure 2.
Fig. 2. Docking of the atomic model of MxiH into the EM density of the Shigella T3SS needle. (A) Molecule A of MxiH (ribbon) with the modeled N-terminal helix (cylinder) is shown as two views rotated by 90° about the long axis of the molecule. (B) End-on view of a 40-Å-thick section of the assembled needle. Each MxiH monomer is shown as in A and colored differently, starting from red and circling the needle to purple. EM density is shown as a blue mesh. (C) Stereo diagram of the side view of the assembled needle, colored as for B. Note that B and C are not shown at the same scale, and the needle assembly has an exterior diameter of 70 Å (16).

Figure 4.
Fig. 4. Characterization of the putative tip-interaction interface of a T3SS needle. (A) Surface representation of the side view of the T3SS needle with each monomer colored differently, starting from red and circling the needle to purple. Residues likely to effect interactions with the tip complex are highlighted as follows: P44 and Q51 in Shigella (white) and the equivalent of D46 in Yersinia (gray). (B) View and coloring as for A, with residues conserved between Shigella MxiH and Yersinia YscF highlighted. Residues conserved in the head domain: L37, P41, N43, P44, L46, L47, A48, and Q51 (white); in the tail domain, N62, S65, V68, K72, D73, I78, Q80, and F82 (gray) are shown for the top circle of the needle. (C Left) Ribbon diagram of LcrV (30) colored N (blue) to C (red) termini. (C Right) Overlay of the C-terminal helices of MxiH (red, residues 45–75) and LcrV (blue, residues 287–317), with all but the overlaid region made transparent to aid visualization. (D) Model of an LcrV tip complex (surface representation, gray) onto the tip of a T3SS needle.

Figures were selected by the author.