Evidence from extended X-ray absorption fine structure and site-specific mutagenesis for zinc fingers in UvrA protein of Escherichia coli |
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Authors: | S Navaratnam G M Myles R W Strange A Sancar |
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Institution: | Research Division, North East Wales Institute, United Kingdom. |
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Abstract: | The UvrA protein is the damage recognition subunit of the Escherichia coli repair enzyme ABC excision nuclease. Sequence analysis of this 940-amino acid protein revealed two regions of sequence homology to the zinc finger motif found in many DNA binding proteins. Physical and chemical analyses indicate about 2 zinc atoms/molecule. We have used extended x-ray absorption fine structure analysis to demonstrate that each of these zinc atoms is coordinated with 4 cysteine residues at a distance of 2.32 +/- 0.2 A. Substitution of one of the cysteines by a histidine, a serine, or an alanine in one of the potential finger sites resulted in a respective decrease in complementing activity. We thus conclude that the two zinc fingers identified by sequence analysis do indeed have zinc finger structure in UvrA protein. |
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