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Structures of Escherichia coli tryptophanase in holo and `semi‐holo' forms
Author(s) -
Kogan Anna,
Raznov Leah,
Gdalevsky Garik Y.,
CohenLuria Rivka,
Almog Orna,
Parola Abraham H.,
Goldgur Yehuda
Publication year - 2015
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 37
ISSN - 2053-230X
DOI - 10.1107/s2053230x15000850
Subject(s) - tryptophanase , chemistry , lyase , pyridoxal phosphate , stereochemistry , crystallography , escherichia coli , crystal (programming language) , crystallization , active site , indole test , crystal structure , cofactor , tryptophan , enzyme , biochemistry , amino acid , gene , organic chemistry , computer science , programming language
Two crystal forms of Escherichia coli tryptophanase (tryptophan indole‐lyase, Trpase) were obtained under the same crystallization conditions. Both forms belonged to the same space group P 4 3 2 1 2 but had slightly different unit‐cell parameters. The holo crystal form, with pyridoxal phosphate (PLP) bound to Lys270 of both polypeptide chains in the asymmetric unit, diffracted to 2.9 Å resolution. The second crystal form diffracted to 3.2 Å resolution. Of the two subunits in the asymmetric unit, one was found in the holo form, while the other appeared to be in the apo form in a wide‐open conformation with two sulfate ions bound in the vicinity of the active site. The conformation of all holo subunits is the same in both crystal forms. The structures suggest that Trpase is flexible in the apo form. Its conformation partially closes upon binding of PLP. The closed conformation might correspond to the enzyme in its active state with both cofactor and substrate bound in a similar way as in tyrosine phenol‐lyase.