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Contrasting effects of mutating active site residues, Aspartic acid 64 and Histidine 187 of <i>Escherichia coli </i>uracil-DNA glycosylase on uracil excision and interaction with an inhibitor protein

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Title Contrasting effects of mutating active site residues, Aspartic acid 64 and Histidine 187 of Escherichia coli uracil-DNA glycosylase on uracil excision and interaction with an inhibitor protein
 
Creator Handa, Priya
Acharya, Narottam
Talawar, Ramappa K
Roy, Sudipta
Varshney, Umesh
 
Description 312-317
Uracil, a promutagenic base, arises in DNA by spontaneous
deamination of cytosine or by the malfunctioning of DNA polymerases. To
maintain the genomic integrity, cells possess a highly conserved base excision
repair enzyme. uracil –DNA glycosylase (UDG). UDGs have a notably high turnover
number and strict specificity for uracil in DNA. UDGs are inhibited

by a small proteinaceous inhibitor. Ugi, which acts as
a transition state substrate mimic. Crystal
structure studies have identified the residues crucial in catalysis, and in
their interaction with Ugi. Here, we report on the  mutational analyses of  D64(D64H and D64N) and H187 (H187C, H187L and
H187R) in the active site pocket of Escherichia coli UDG. The mutants

were compromised in uracil excision by ~ 200-25,000
fold when compared to the native protein. In contrast. our analysis of the in
vivo formed UDG-Ugi complexes on urea gels shows that D64 and H187 contribute
minimally to the interaction of the two proteins. Thus, our findings prov de
further evidence to the primary functi on of D64 and H187 in catalysis.
 
Date 2012-12-08T16:22:10Z
2012-12-08T16:22:10Z
2002-10
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://hdl.handle.net/123456789/15216
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJBB Vol.39(5) [October 2002]