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Plastic adaptation toward mutations in proteins: Structural comparison of thymidylate synthases
Author(s) -
Perry Kathy M.,
Fauman Eric B.,
FinerMoore Janet S.,
Montfort William R.,
Maley Gladys F.,
Maley Frank,
Stroud Robert M.
Publication year - 1990
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340080406
Subject(s) - lactobacillus casei , chemistry , crystallography , resolution (logic) , residue (chemistry) , biochemistry , fermentation , artificial intelligence , computer science
The structure of thymidylate synthase (TS) from Escherichia coli was solved from cubic crystals with a = 133 Å grown under reducing conditions at pH 7.0, and refined to R = 22% at 2.1 Å resolution. The structure is compared with that from Lactobacillus casei solved to R = 21% at 2.3 Å resolution. The structures are compared using a difference distance matrix, which identifies a common core of residues that retains the same relationship to one another in both species. After subtraction of the effects of a 50 amino acid insert present in Lactobacillus casei , differences in position of atoms correlate with temperature factors and with distance from the nearest substituted residue. The dependence of structural difference on thermal factor is parameterized and reflects both errors in coordinates that correlate with thermal factor, and the increased width of the energy well in which atoms of high thermal factor lie. The dependence of structural difference on distance from the nearest substitution also depends on thermal factors and shows an exponential dependence with half maximal effect at 3.0 Å from the substitution. This represents the plastic accommodation of the protein which is parameterized in terms of thermal B factor and distance from a mutational change.