Cloning, sequence analysis, and overexpression of Escherichia coli folK, the gene coding for 7,8-dihydro-6-hydroxymethylpterin-pyrophosphokinase. |
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| Authors: | T L Talarico P H Ray I K Dev B M Merrill and W S Dallas |
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| Affiliation: | Department of Molecular Genetics and Microbiology, Burroughs Wellcome Co., Research Triangle Park, North Carolina 27709. |
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| Abstract: | The gene coding for the Escherichia coli enzyme 7,8-dihydro-6-hydroxymethylpterin-pyrophosphokinase has been cloned and sequenced. This gene, designated folK, codes for a protein of 159 amino acids, including an amino-terminal methionine. The protein was overexpressed in E. coli MC4100 by cloning the gene behind the lacUV5 promoter in a high-copy-number plasmid. The enzyme was purified to homogeneity. Amino-terminal analysis of the purified protein showed that the amino-terminal methionine had been removed. The compositional molecular mass (17,945 Da) was identical to the molecular mass determined by mass spectrometry. The enzyme was observed to have a large number of proline residues and migrated anomalously in sodium dodecyl sulfate-polyacrylamide gels, with an apparent molecular mass of 23,000 Da. |
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