PDBsum entry 2c1c

Hydrolase

PDB id: 2c1c

Contents

Protein chains

312 a.a. *

Metals

_Y1 ×2

_ZN ×2

Waters ×347

* Residue conservation analysis

PDB id:

2c1c

Name:

Hydrolase

Title:

Structural basis of the resistance of an insect carboxypeptidase to plant protease inhibitors

Structure:

Carboxypeptidase b. Chain: a, b. Engineered: yes

Source:

Helicoverpa zea. Corn earworm. Organism_taxid: 7113. Tissue: epithelium. Expressed in: pichia pastoris. Expression_system_taxid: 4922.

Resolution:

2.30Å R-factor: 0.215 R-free: 0.292

Authors:

A.Bayes,M.Comellas-Bigler,M.Rodriguez De La Vega,K.Maskos,W.Bode, F.X.Aviles,M.A.Jongsma,J.Beekwilder,J.Vendrell

Key ref:

A.Bayés et al. (2005). Structural basis of the resistance of an insect carboxypeptidase to plant protease inhibitors. Proc Natl Acad Sci U S A, 102, 16602-16607. PubMed id: 16260742 DOI: 10.1073/pnas.0505489102

Date:

12-Sep-05 Release date: 19-Oct-05

Protein chains

Q3T905  (CBPB_HELZE) -  Carboxypeptidase B from Helicoverpa zea

Seq: 429 a.a.

Struc: 312 a.a.

Enzyme reactions

• Enzyme class: E.C.3.4.17.2 - carboxypeptidase B.
• Reaction: Peptidyl-L-lysine(or L-arginine) + H(2)O = peptide + L-lysine(or L- arginine)
• Cofactor: Zn(2+)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Key reference

DOI no: 10.1073/pnas.0505489102

Proc Natl Acad Sci U S A 102:16602-16607 (2005)

PubMed id: 16260742

Structural basis of the resistance of an insect carboxypeptidase to plant protease inhibitors.

A.Bayés, M.Comellas-Bigler, M.Rodríguez de la Vega, K.Maskos, W.Bode, F.X.Aviles, M.A.Jongsma, J.Beekwilder, J.Vendrell.

ABSTRACT

Corn earworm (Helicoverpa zea), also called tomato fruitworm, is a common pest of many Solanaceous plants. This insect is known to adapt to the ingestion of plant serine protease inhibitors by using digestive proteases that are insensitive to inhibition. We have now identified a B-type carboxypeptidase of H. zea (CPBHz) insensitive to potato carboxypeptidase inhibitor (PCI) in corn earworm. To elucidate the structural features leading to the adaptation of the insect enzyme, the crystal structure of the recombinant CPBHz protein was determined by x-ray diffraction. CPBHz is a member of the A/B subfamily of metallocarboxypeptidases, which displays the characteristic metallocarboxypeptidase alpha/beta-hydrolase fold, and does not differ essentially from the previously described Helicoverpa armigera CPA, which is very sensitive to PCI. The data provide structural insight into several functional properties of CPBHz. The high selectivity shown by CPBHz for C-terminal lysine residues is due to residue changes in the S1' substrate specificity pocket that render it unable to accommodate the side chain of an arginine. The insensitivity of CPBHz to plant inhibitors is explained by the exceptional positioning of two of the main regions that stabilize other carboxypeptidase-PCI complexes, the beta8-alpha9 loop, and alpha7 together with the alpha7-alpha8 loop. The rearrangement of these two regions leads to a displacement of the active-site entrance that impairs the proper interaction with PCI. This report explains a crystal structure of an insect protease and its adaptation to defensive plant protease inhibitors.

Selected figure(s)

Figure 1.
Fig. 1. Stereo ribbon plot representation of CPBHz. The two histidines and the glutamic acid residues coordinating the zinc atom are shown as stick models in green, the zinc atom is shown as a silver sphere, and the single disulfide bridge present in the structure is shown in blue. The polypeptide fold consists of a core of eight twisted -sheets surrounded by eight -helices. Figure generated with MOLSCRIPT (31) and RASTER 3D (32).

Figure 3.
Fig. 3. Stereoview of a structural superimposition of H. zea carboxypeptidase B in orange, human carboxypeptidase B in green, and H. armigera carboxypeptidase A, in purple. Trp-277A of CPBHz and residues Trp-277B and Tyr-277 in human CPAHa and CPBh, respectively, are represented as stick models; the arrow indicates the entrance to the active-site cleft. The zinc ion is shown in silver. The orientation of the molecule is the same as in Fig. 1.

Figures were selected by an automated process.