PDBsum entry 1c78

Hydrolase

PDB id: 1c78

Contents

Protein chains

130 a.a. *

* Residue conservation analysis

References listed in PDB file

Key reference

Title

Crystal structure of a staphylokinase: variant a model for reduced antigenicity.

Authors

Y.Chen, G.Song, F.Jiang, L.Feng, X.Zhang, Y.Ding, M.Bartlam, A.Yang, X.Ma, S.Ye, Y.Liu, H.Tang, H.Song, Z.Rao.

Ref.

Eur J Biochem, 2002, 269, 705-711. [DOI no: 10.1046/j.0014-2956.2001.02706.x]

PubMed id

11856331

Abstract

Staphylokinase (SAK) is a 15.5-kDa protein from Staphylococcus aureus that activates plasminogen by forming a 1 : 1 complex with plasmin. Recombinant SAK has been shown in clinical trials to induce fibrin-specific clot lysis in patients with acute myocardial infarction. However, SAK elicits high titers of neutralizing antibodies. Biochemical and protein engineering studies have demonstrated the feasibility of generating SAK variants with reduced antigenicity yet intact thrombolytic potency. Here, we present X-ray crystallographic evidence that the SAK(S41G) mutant may assume a dimeric structure. This dimer model, at 2.3-A resolution, could explain a major antigenic epitope (residues A72-F76 and residues K135-K136) located in the vicinity of the dimer interface as identified by phage-display. These results suggest that SAK antigenicity may be reduced by eliminating dimer formation. We propose several potential mutation sites at the dimer interface that may further reduce the antigenicity of SAK.

Figure 3.
Fig. 3. Views of the salt bridge and hydrogen bonding networks (A) and the hydrophobic residues in the dimer interface (B). (A) Close up view of the salt bridge and hydrogen bonding networks in the dimer interface; more details are shown in Table 2 Go-. (B) The hydrophobic residues in the dimer interface. The figures are drawn with molscript[34] and rendered by raster3d[35].

Figure 4.
Fig. 4. The top view of the SAK – dimer interface (A ) and mapping of residues involved in the antigenic sites and dimer interfaces (B). (A) The major antigenic area I (residues 72–76, and residues 135–136) in the close vicinity of the dimer interface is colored in red. The mapping ofresidues involved in the antigenic sites and dimer interfaces. (B) The – dimer interface is shown by a dashed line. The mutated sites located in the – dimer interface are colored in purple; the antigenic sites are colored in red, the other – dimer interface residues in green. The figures are drawn with grasp[36].

The above figures are reprinted by permission from the Federation of European Biochemical Societies: Eur J Biochem (2002, 269, 705-711) copyright 2002.