Alteration of T4 lysozyme structure by second-site reversion of deleterious mutations.
Mutations that suppress the defects introduced into T4 lysozyme by single amino acid substitutions were isolated and characterized. Among 53 primary sites surveyed, 8 yielded second-site revertants; a total of 18 different mutants were obtained. Most of the restorative mutations exerted global effects, generally increasing lysozyme function in a number of primary mutant contexts. Six of them were more specific, suppressing only certain specific deleterious primary substitutions, or diminishing the function of lysozymes bearing otherwise nondeleterious primary substitutions. Some variants of proteins bearing primary substitutions at the positions of Asp 20 and Ala 98 are inferred to have significantly altered structures.
Poteete
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Department of Molecular Genetics & Microbiology, University of Massachusetts Medical Center, Worcester 01655, USA. tpoteete@ummed.edu
Rennell
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Bouvier
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Hardy
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D017100:Bacteriophage P22 / Q000235:genetics; D017122:Bacteriophage T4 / Q000201:enzymology / Q000235:genetics*; D005814:Genes, Viral; D009113:Muramidase / Q000737:chemistry* / Q000235:genetics*; D009154:Mutation; D011994:Recombinant Proteins; D012486:Salmonella typhimurium / Q000821:virology; D013489:Suppression, Genetic
D011994:Recombinant Proteins; D009113:Muramidase