scholarly journals Insights into the role of Val45 and Gln182 of Escherichia coli MutY in DNA substrate binding and specificity

2009 ◽  
Vol 10 (1) ◽  
pp. 19 ◽  
Author(s):  
Po-Wen Chang ◽  
Amrita Madabushi ◽  
A-Lien Lu
Keyword(s):  
Escherichia Coli ◽  
Substrate Binding ◽  
Dna Substrate

scholarly journals Studies on the mechanism of hydroxymethylbilane synthase concerning the role of arginine residues in substrate binding

1991 ◽  
Vol 275 (2) ◽  
pp. 447-452 ◽  
Author(s):  
M Lander ◽  
A R Pitt ◽  
P R Alefounder ◽  
D Bardy ◽  
C Abell ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Kinetic Parameters ◽  
Substrate Binding ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Side Chains ◽  
Enzyme Substrate ◽  
Arginine Residues

The role of conserved arginine residues in hydroxymethylbilane synthase was investigated by replacing these residues in the enzyme from Escherichia coli with leucine residues by using site-directed mutagenesis. The kinetic parameters for these mutant enzymes and studies on the formation of intermediate enzyme-substrate complexes indicate that several of these arginine residues are involved in binding the carboxylate side chains of the pyrromethane cofactor and the growing oligopyrrole chain.

Role of CH/π interactions in substrate binding by Escherichia coli β-galactosidase

2004 ◽  
Vol 339 (13) ◽  
pp. 2275-2280 ◽  
Author(s):  
Vojtěch Spiwok ◽  
Petra Lipovová ◽  
Tereza Skálová ◽  
Eva Buchtelová ◽  
Jindřich Hašek ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Substrate Binding ◽  
Π Interactions

scholarly journals Genetic Evidence for the Requirement of RecA Loading Activity in SOS Induction after UV Irradiation in Escherichia coli

2006 ◽  
Vol 188 (14) ◽  
pp. 5024-5032 ◽  
Author(s):  
Ivana Ivančić-Baće ◽  
Ignacija Vlašić ◽  
Erika Salaj-Šmic ◽  
Krunoslav Brčić-Kostić
Keyword(s):  
Escherichia Coli ◽  
Uv Irradiation ◽  
Constitutive Expression ◽  
Recq Helicase ◽  
Sos Induction ◽  
Dna Damaging Agents ◽  
Lexa Repressor ◽  
Recbcd Enzyme ◽  
Dna Substrate

ABSTRACT The SOS response in Escherichia coli results in the coordinately induced expression of more than 40 genes which occurs when cells are treated with DNA-damaging agents. This response is dependent on RecA (coprotease), LexA (repressor), and the presence of single-stranded DNA (ssDNA). A prerequisite for SOS induction is the formation of a RecA-ssDNA filament. Depending on the DNA substrate, the RecA-ssDNA filament is produced by either RecBCD, RecFOR, or a hybrid recombination mechansim with specific enzyme activities, including helicase, exonuclease, and RecA loading. In this study we examined the role of RecA loading activity in SOS induction after UV irradiation. We performed a genetic analysis of SOS induction in strains with a mutation which eliminates RecA loading activity in the RecBCD enzyme (recB1080 allele). We found that RecA loading activity is essential for SOS induction. In the recB1080 mutant RecQ helicase is not important, whereas RecJ nuclease slightly decreases SOS induction after UV irradiation. In addition, we found that the recB1080 mutant exhibited constitutive expression of the SOS regulon. Surprisingly, this constitutive SOS expression was dependent on the RecJ protein but not on RecFOR, implying that there is a different mechanism of RecA loading for constitutive SOS expression.

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