3lzm
From Proteopedia
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STRUCTURAL STUDIES OF MUTANTS OF T4 LYSOZYME THAT ALTER HYDROPHOBIC STABILIZATION
Overview
Multiple replacements at amino acid position 3 of bacteriophage T4, lysozyme have shown that the conformational stability of the protein is, directly governed by the hydrophobicity of the residue substituted, (Matsumura, M., Becktel, W. J., and Matthews, B. W. (1988) Nature 334, 406-410). Of the 13 mutant lysozymes made by site-directed mutagenesis, two variants, one with valine (I3V) and the other with tyrosine (I3Y), were crystallized and their structures solved. In this report we describe, the crystal structures of these variants at 1.7 A resolution. While the, structure of the I3V mutant is essentially the same as that of wild-type, lysozyme, the I3Y mutant has substantial changes in its structure. The, most significant of these are that the side chain of the tyrosine is not, accommodated within the interior of the protein and the amino-terminal, polypeptide (residues 1-9) moves 0.6-1.1 A relative to the wild-type, structure. Using coordinates based on the wild-type and available mutant, structures, solvent accessible surface area of residue 3 as well as the, adjacent 9 residues in the folded form were calculated. The free energy of, stabilization based on the transfer of these residues from a fully, extended form to the interior to the folded protein was found to correlate, well with the protein stability determined by thermodynamic analysis. The, enhanced thermostability of the variant Ile-3----Leu, relative to, wild-type lysozyme, can also be rationalized by surface-area calculations, based on a model-built structure. Noncrystallization of most lysozyme, variants at position 3 appears to be due to disruption of intermolecular, contacts in the crystal. The Ile-3----Val variant is closely isomorphous, with wild-type and maintains the same crystal contacts. In the, Ile-3----Tyr variant, however, a new set of contacts is made in which, direct protein-protein hydrogen bonds are replaced by, protein-water-protein hydrogen bonds as well as a novel hydrogen bond, involving the phenolic hydroxyl of the substituted tyrosine.
About this Structure
3LZM is a Single protein structure of sequence from Bacteriophage t4. Active as Lysozyme, with EC number 3.2.1.17 Full crystallographic information is available from OCA.
Reference
Structural studies of mutants of T4 lysozyme that alter hydrophobic stabilization., Matsumura M, Wozniak JA, Sun DP, Matthews BW, J Biol Chem. 1989 Sep 25;264(27):16059-66. PMID:2674124
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