260l
AN ADAPTABLE METAL-BINDING SITE ENGINEERED INTO T4 LYSOZYME
Structural highlights
FunctionENLYS_BPT4 Endolysin with lysozyme activity that degrades host peptidoglycans and participates with the holin and spanin proteins in the sequential events which lead to the programmed host cell lysis releasing the mature viral particles. Once the holin has permeabilized the host cell membrane, the endolysin can reach the periplasm and break down the peptidoglycan layer.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIt is not easy to find candidate sites within a given protein where the geometry of the polypeptide chain matches that of metal-binding sites in known protein structures. By choosing a location in T4 lysozyme that is inherently flexible, it was possible to engineer a two-histidine site that binds different divalent cations. Crystallographic analysis shows that the geometry of binding of zinc is distorted tetrahedral while that of cobalt and nickel is octahedral. Insofar as spectroscopic data can be measured, they indicate that similar modes of coordination are retained in solution. The two substitutions, Thr21 --> His and Thr142 --> His, lie, respectively, on the surface of the N- and C-terminal domains on opposite sides of the active site cleft. The design takes advantage of hinge-bending motion which allows the binding site to adapt to the most favorable ligand geometry for the metal. Introduction of the two histidines increases the melting temperature of the protein by 2.0 degrees C at pH 7.4. Metal binding further increases the melting temperature, but only by a small amount (up to 1.5 degrees C). A third substitution, Gln141 --> His, which could act as a third ligand in principle, does not do so, demonstrating the difficulty in mimicking naturally occurring metal-binding sites. Use of a non-rigid region in T4 lysozyme to design an adaptable metal-binding site.,Wray JW, Baase WA, Ostheimer GJ, Zhang XJ, Matthews BW Protein Eng. 2000 May;13(5):313-21. PMID:10835104[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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