PDBsum entry 1bfo

Antibody

PDB id: 1bfo

Contents

Protein chains

214 a.a. *

216 a.a. *

Waters ×387

* Residue conservation analysis

PDB id:

1bfo

Name:

Antibody

Title:

Campath-1g igg2b rat monoclonal fab

Structure:

Campath-1g antibody. Chain: a, c, e, g. Fragment: fab fragment. Campath-1g antibody. Chain: b, d, f, h. Fragment: fab fragment

Source:

Rattus rattus. Black rat. Organism_taxid: 10117. Secretion: ascitic fluid. Secretion: ascitic fluid

Biol. unit:

Dimer (from PQS)

Resolution:

2.60Å R-factor: 0.192 R-free: 0.263

Authors:

G.M.T.Cheetham,G.Hale,H.Waldmann,A.C.Bloomer

Key ref:

G.M.Cheetham et al. (1998). Crystal structures of a rat anti-CD52 (CAMPATH-1) therapeutic antibody Fab fragment and its humanized counterpart. J Mol Biol, 284, 85-99. PubMed id: 9811544 DOI: 10.1006/jmbi.1998.2157

Date:

20-May-98 Release date: 16-Mar-99

Protein chains

P01835  (KACB_RAT) -  Ig kappa chain C region, B allele from Rattus norvegicus

Seq: 106 a.a.

Struc: 214 a.a.*

Protein chains

P20761  (IGG2B_RAT) -  Ig gamma-2B chain C region from Rattus norvegicus

Seq: 333 a.a.

Struc: 216 a.a.

* PDB and UniProt seqs differ at 9 residue positions (black crosses)

DOI no: 10.1006/jmbi.1998.2157

J Mol Biol 284:85-99 (1998)

PubMed id: 9811544

Crystal structures of a rat anti-CD52 (CAMPATH-1) therapeutic antibody Fab fragment and its humanized counterpart.

G.M.Cheetham, G.Hale, H.Waldmann, A.C.Bloomer.

ABSTRACT

The CAMPATH-1 family of antibodies are able systematically to lyse human lymphocytes with human complement by targeting the small cell-surface glycoprotein CD52, commonly called the CAMPATH-1 antigen. These antibodies have been used clinically for several years, providing therapy for patients with a variety of immunologically mediated diseases. We report here the first X-ray crystallographic analyses of a Fab fragment from a rat antibody, the original therapeutic monoclonal CAMPATH-1G and its humanized counterpart CAMPATH-1H, into which the six complementarity-determining regions of the rat antibody have been introduced. These structures have been refined at 2.6 A and 3.25 A resolution, respectively. The VL domains of adjacent molecules of CAMPATH-1H form a symmetric dimer within the crystals with an inter-molecular extended beta-sheet as seen in light chain dimers of the kappa class. Crystals of CAMPATH-1G have translational pseudo-symmetry. Within the antibody-combining sites, which are dominated by the protrusion of LysH52b and LysH53 from hypervariable loop H2, the charge distribution and overall integrity are highly conserved, but large changes in the position of loop H1 are observed and an altered conformation of loop H2. The major determinants of this are framework residues H71 and H24, whose identity differs in these two antibodies. These structures provide a detailed structural insight into the transplantation of an intact antibody-combining site between a rodent and a human framework, and provide an increased understanding of the specificity and antigen affinity of this pair of CAMPATH-1 antibodies for CD52. This study forms the structural basis for future modification and design of more effective antibodies to this important antigen.

Selected figure(s)

Figure 3.
Figure 3. The structure of the inter-molecular V[L] -V[L]dimer seen in CAMH. A complete Fab is shown with the V[L]and C[L]domains in green and the V[H]and C[H]domains in yellow. In cyan is shown the V[L] domain of an adjacent molecule at position ( -y, -x 1/6 - z), related by a vertical crystallographic 2-fold axis lying approximately in the plane of the paper. The side-chains ArgL18 and AspL70', which make a symmetrical pair of salt-bridges, are labelled. There is also a hydrogen bond between ArgL18 and SerL7'. The antiparallel interaction between the first b-strands of the two V[L] domains, showing the extent of the intermolecular hydrogen bonding between residues L9-L12, viewed from the outside of the dimer towards the interface is shown in detail (RIBBONS; [Carson 1991]).

Figure 6.
Figure 6. The antibody-combining site. (a) The molecular surface (drawn by the program GRASP; [Nicholl and Honig 1991]) of the CAMH antibody-combining site coloured by electrostatic potential (blue is positive, red is negative and white is neutral) viewed in an orientation similar to that in Figure 5(c) and (d). (b) and (c) Atomic representations (drawn by the program RIBBONS; [Carson 1991]) of (b) CAMH and (c) CAMG, corresponding to approximately the same orientation as that in (a).

The above figures are reprinted by permission from Elsevier: J Mol Biol (1998, 284, 85-99) copyright 1998.

Figures were selected by an automated process.