ISSN:
0887-3585
Keywords:
phosphotyrosine linkage
;
protein-DNA transesterification
;
enzyme mechanism
;
DNA-protein covalent complex
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Tyrosine 319 of E. coli topoisomerase I is shown to be the activesite tyrosine that becomes covalently attached to a DNA 5′ phosphoryl group during the transient breakage of a DNA internucleotide bond by the enzyme. The tyrosine was mapped by trapping the covalent complex between the DNA and DNA topoisomerase I, digesting the complex exhaustively with trypsin, and sequencing the DNA-linked tryptic peptide. Site-directed mutagenesis converting Tyr-319 to a serine or phenylalanine completely inactivates the enzyme. The structure of the enzyme andits catalysis of DNA strand breakage, passage, and rejoining are discussed in terms of the available information.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prot.340060305
