title: Expression, purification, and characterization of thymidylate synthase from Lactococcus lactis.
abstract: The thymidylate synthase (TS) gene from Lactococcus lactis has been highly expressed in Escherichia coli. The TS protein was purified by sequential chromatography on Q-Sepharose and phenyl-Sepharose. Six grams of cell pellet yielded 140 mg of homogeneous TS. TS is a highly conserved enzyme, and several of the conserved amino acid residues that have been implicated in catalytic function are altered in L. lactis TS. By use of a 3-dimensional homology model, we have predicted covariant changes that might compensate for these differences. With the large amounts of L. lactis TS now available, studies can be pursued to understand the structure-function relationships of this enzyme compared to other TSs and to confirm the presumed roles of the compensatory changes predicted in the homology model.
authors.affiliation: Department of Biochemistry, University of California, San Francisco 94143.
authors.forename: P J
authors.initials: PJ
authors.lastname: Greene
authors.forename: P L
authors.initials: PL
authors.lastname: Yu
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: C A
authors.initials: CA
authors.lastname: Schiffer
authors.forename: D
authors.initials: D
authors.lastname: Santi
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003460:Crystallization; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009994:Osmolar Concentration; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D013940:Thymidylate Synthase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D011994:Recombinant Proteins; D013940:Thymidylate Synthase