PDBsum entry 2ccl

Cell adhesion

PDB id: 2ccl

Contents

Protein chains

149 a.a. *

62 a.a. *

Ligands

PO4 ×2

Metals

_CA ×4

Waters ×496

* Residue conservation analysis

PDB id:

2ccl

Name:

Cell adhesion

Title:

The s45a, t46a mutant of the type i cohesin-dockerin complex from the cellulosome of clostridium thermocellum

Structure:

Cellulosomal scaffolding protein a. Chain: a, c. Fragment: cohesin 2 domain, residues 181-328. Synonym: cellulosomal glycoprotein s1/sl, cellulose integrating protein a, cohesin. Engineered: yes. Endo-1,4-beta-xylanase y. Chain: b, d. Fragment: residues 730-791.

Source:

Clostridium thermocellum. Organism_taxid: 1515. Expressed in: escherichia coli. Expression_system_taxid: 562. Expression_system_taxid: 562

Resolution:

2.03Å R-factor: 0.183 R-free: 0.230

Authors:

A.L.Carvalho,F.M.V.Dias,J.A.M.Prates,L.M.A.Ferreira,H.J.Gilbert, G.J.Davies,M.J.Romao,C.M.G.A.Fontes

Key ref:

A.L.Carvalho et al. (2007). Evidence for a dual binding mode of dockerin modules to cohesins. Proc Natl Acad Sci U S A, 104, 3089-3094. PubMed id: 17360613 DOI: 10.1073/pnas.0611173104

Date:

16-Jan-06 Release date: 13-Feb-07

Protein chains

Q06851  (CIPA_CLOTH) -  Cellulosomal-scaffolding protein A from Acetivibrio thermocellus (strain ATCC 27405 / DSM 1237 / JCM 9322 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372)

Seq: 1853 a.a.

Struc: 149 a.a.*

Protein chains

P51584  (XYNY_ACETH) -  Endo-1,4-beta-xylanase Y from Acetivibrio thermocellus

Seq: 1077 a.a.

Struc: 62 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains B, D: E.C.3.2.1.8 - endo-1,4-beta-xylanase.
• Reaction: Endohydrolysis of 1,4-beta-D-xylosidic linkages in xylans.

DOI no: 10.1073/pnas.0611173104

Proc Natl Acad Sci U S A 104:3089-3094 (2007)

PubMed id: 17360613

Evidence for a dual binding mode of dockerin modules to cohesins.

A.L.Carvalho, F.M.Dias, T.Nagy, J.A.Prates, M.R.Proctor, N.Smith, E.A.Bayer, G.J.Davies, L.M.Ferreira, M.J.Romão, C.M.Fontes, H.J.Gilbert.

ABSTRACT

The assembly of proteins that display complementary activities into macromolecular complexes is critical to cellular function. One such enzyme complex, of environmental significance, is the plant cell wall degrading apparatus of anaerobic bacteria, termed the cellulosome. The complex assembles through the interaction of enzyme-derived "type I dockerin" modules with the multiple "cohesin" modules of the scaffolding protein. Clostridium thermocellum type I dockerin modules contain a duplicated 22-residue sequence that comprises helix-1 and helix-3, respectively. The crystal structure of a C. thermocellum type I cohesin-dockerin complex showed that cohesin recognition was predominantly through helix-3 of the dockerin. The sequence duplication is reflected in near-perfect 2-fold structural symmetry, suggesting that both repeats could interact with cohesins by a common mechanism in wild-type (WT) proteins. Here, a helix-3 disrupted mutant dockerin is used to visualize the reverse binding in which the dockerin mutant is indeed rotated 180 degrees relative to the WT dockerin such that helix-1 now dominates recognition of its protein partner. The dual binding mode is predicted to impart significant plasticity into the orientation of the catalytic subunits within this supramolecular assembly, which reflects the challenges presented by the degradation of a heterogeneous, recalcitrant, insoluble substrate by a tethered macromolecular complex.

Selected figure(s)

Figure 1.
Fig. 1. The cellulosome. (a) Schematic of the cellulosome. The type I dockerins, appended to the catalytic subunits, interact with the cohesin modules on the scaffoldin (CipA) leading to the formation of the supramolecular cellulosome complex. The type II dockerin on CipA, by binding to a type II cohesin on the bacterial membrane, tethers the cellulosome to the surface of C. thermocellum. (b) Internal symmetry of the WT dockerin in complex with cohesin. Not only do residues 1–22 overlap with 35–56, but the reverse is also true, because the dockerin shows internal 2-fold symmetry (panel b adapted from ref. 18).

Figure 3.
Fig. 3. The Coh-Doc interface of the native (in orange) and S45A-T46A mutant (in blue) type I complexes. (a) Stick representation of the hydrophobic residues on the surface of the cohesin modules (in ribbon representation). The dockerin modules are represented by their molecular surfaces. (b) Stick representation of the hydrophobic residues on the surface of the dockerin modules (in ribbon representation). The cohesin modules are represented by their molecular surfaces. (c) Stick representation of the hydrogen-bond network in the interface of the Coh-DocS45A-T46A complex (in ribbon representation). Carbon atoms are shown in yellow, oxygens are shown in red, and nitrogens are shown in blue. All pictures were produced with the CCP4 mg program (42).

Figures were selected by an automated process.