1L16

STRUCTURAL ANALYSIS OF THE TEMPERATURE-SENSITIVE MUTANT OF BACTERIOPHAGE T4 LYSOZYME, GLYCINE 156 (RIGHT ARROW) ASPARTIC ACID

Summary for 1L16

• Entry DOI: 10.2210/pdb1l16/pdb
• Related: 1L01 1L02 1L03 1L04 1L05 1L06 1L07 1L08 1L09 1L10 1L11 1L12 1L13 1L14 1L15 1L17 1L18 1L19 1L20 1L21 1L22 1L23 1L24 1L25 1L26 1L27 1L28 1L29 1L30 1L31 1L32 1L33 1L34 1L35 1L36 2LZM
• Descriptor: T4 LYSOZYME (2 entities in total)
• Functional Keywords: hydrolase (o-glycosyl)
• Biological source: Enterobacteria phage T4
• Total number of polymer chains: 1
• Total formula weight: 18720.50

Authors

Gray, T.M.,Matthews, B.W. (deposition date: 1988-02-05, release date: 1988-04-16, Last modification date: 2024-05-22)

Primary citation

Gray, T.M.,Matthews, B.W.
Structural analysis of the temperature-sensitive mutant of bacteriophage T4 lysozyme, glycine 156----aspartic acid.
J.Biol.Chem., 262:16858-16864, 1987

PubMed Abstract: The structure of the mutant of bacteriophage T4 lysozyme in which Gly-156 is replaced by aspartic acid is described. The lysozyme was isolated by screening for temperature-sensitive mutants and has a melting temperature at pH 6.5 that is 6.1 degrees C lower than wild type. The mutant structure is destabilized, in part, because Gly-156 has conformational angles (phi, psi) that are not optimal for a residue with a beta-carbon. High resolution crystallographic refinement of the mutant structure (R = 17.7% at 1.7 A resolution) shows that the Gly----Asp substitution does not significantly alter the configurational angles (phi, psi) but forces the backbone to move, as a whole, approximately 0.6 A away from its position in wild-type lysozyme. This induced strain weakens a hydrogen bond network that exists in the wild-type structure and also contributes to the reduced stability of the mutant lysozyme. The introduction of an acidic side chain reduces the overall charge on the molecule and thereby tends to increase the stability of the mutant structure relative to wild type. However, at neutral pH this generalized electrostatic stabilization is offset by specific electrostatic repulsion between Asp-156 and Asp-92. The activity of the mutant lysozyme is approximately 50% that of wild-type lysozyme. This reduction in activity might be due to introduction of a negative charge and/or perturbation of the surface of the molecule in the region that is assumed to interact with peptidoglycan substrates.

PubMed: 3680274

Experimental method

X-RAY DIFFRACTION (1.7 Å)