Mechanism of Action of Escherichia coli Formamidopyrimidine N-Glycosylase and Endonuclease V

1999 ◽  
pp. 209-219
Author(s):  
Yoke W. Kow ◽  
Lois E. Rabow
Keyword(s):  
Escherichia Coli ◽  
Mechanism Of Action ◽  
Endonuclease V

scholarly journals Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Tessa B. Moyer ◽  
Ashleigh L. Purvis ◽  
Andrew J. Wommack ◽  
Leslie M. Hicks
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Antimicrobial Peptides ◽  
Mechanism Of Action ◽  
Gram Negative Bacteria ◽  
Amaranthus Tricolor ◽  
Core Motif ◽  
Gram Negative ◽  
E Coli ◽  
Membrane Lysis

Abstract Background Plant defensins are a broadly distributed family of antimicrobial peptides which have been primarily studied for agriculturally relevant antifungal activity. Recent studies have probed defensins against Gram-negative bacteria revealing evidence for multiple mechanisms of action including membrane lysis and ribosomal inhibition. Herein, a truncated synthetic analog containing the γ-core motif of Amaranthus tricolor DEF2 (Atr-DEF2) reveals Gram-negative antibacterial activity and its mechanism of action is probed via proteomics, outer membrane permeability studies, and iron reduction/chelation assays. Results Atr-DEF2(G39-C54) demonstrated activity against two Gram-negative human bacterial pathogens, Escherichia coli and Klebsiella pneumoniae. Quantitative proteomics revealed changes in the E. coli proteome in response to treatment of sub-lethal concentrations of the truncated defensin, including bacterial outer membrane (OM) and iron acquisition/processing related proteins. Modification of OM charge is a common response of Gram-negative bacteria to membrane lytic antimicrobial peptides (AMPs) to reduce electrostatic interactions, and this mechanism of action was confirmed for Atr-DEF2(G39-C54) via an N-phenylnaphthalen-1-amine uptake assay. Additionally, in vitro assays confirmed the capacity of Atr-DEF2(G39-C54) to reduce Fe3+ and chelate Fe2+ at cell culture relevant concentrations, thus limiting the availability of essential enzymatic cofactors. Conclusions This study highlights the utility of plant defensin γ-core motif synthetic analogs for characterization of novel defensin activity. Proteomic changes in E. coli after treatment with Atr-DEF2(G39-C54) supported the hypothesis that membrane lysis is an important component of γ-core motif mediated antibacterial activity but also emphasized that other properties, such as metal sequestration, may contribute to a multifaceted mechanism of action.

scholarly journals Production of 3-Nitrosoindole Derivatives by Escherichia coli during Anaerobic Growth

2009 ◽  
Vol 191 (17) ◽  
pp. 5369-5376 ◽  
Author(s):  
Young-Man Kwon ◽  
Bernard Weiss
Keyword(s):  
Escherichia Coli ◽  
Nitrous Acid ◽  
Anaerobic Growth ◽  
Functional Genes ◽  
Initial Reaction ◽  
Endonuclease V ◽  
Tryptophanase Activity ◽  
K 12 ◽  
Metabolic Reduction ◽  
Dna Repair Mutants

ABSTRACT When Escherichia coli K-12 is grown anaerobically in medium containing tryptophan and sodium nitrate, it produces red compounds. The reaction requires functional genes for trytophanase (tnaA), a tryptophan permease (tnaB), and a nitrate reductase (narG), as well as a natural drop in the pH of the culture. Mass spectrometry revealed that the purified chromophores had mass/charge ratios that closely match those for indole red, indoxyl red, and an indole trimer. These compounds are known products of chemical reactions between indole and nitrous acid. They are derived from an initial reaction of 3-nitrosoindole with indole. Apparently, nitrite that is produced from the metabolic reduction of nitrate is converted in the acid medium to nitrous acid, which leads to the nitrosation of the indole that is generated by tryptophanase. An nfi (endonuclease V) mutant and a recA mutant were selectively killed during the period of chromophore production, and a uvrA strain displayed reduced growth. These effects depended on the addition of nitrate to the medium and on tryptophanase activity in the cells. Unexpectedly, the killing of a tnaA + nfi mutant was not accompanied by marked increases in mutation frequencies for several traits tested. The vulnerability of three DNA repair mutants indicates that a nitrosoindole or a derivative of a nitrosoindole produces lethal DNA damage.

scholarly journals Escherichia coli S-adenosylhomocysteine/5′-methylthioadenosine nucleosidase. Purification, substrate specificity and mechanism of action

1985 ◽  
Vol 232 (2) ◽  
pp. 335-341 ◽  
Author(s):  
F Della Ragione ◽  
M Porcelli ◽  
M Cartenì-Farina ◽  
V Zappia ◽  
A E Pegg
Keyword(s):  
Escherichia Coli ◽  
Enzyme Activity ◽  
Mechanism Of Action ◽  
Specific Activity ◽  
Maximal Rate ◽  
Purification Procedure ◽  
Protein Affinity ◽  
Naturally Occurring ◽  
Purine Ring ◽  
Ribose Moiety

S-Adenosylhomocysteine/5′-methylthioadenosine nucleosidase (EC 3.2.2.9) was purified to homogeneity from Escherichia coli to a final specific activity of 373 mumol of 5′-methylthioadenosine cleaved/min per mg of protein. Affinity chromatography on S-formycinylhomocysteine-Sepharose is the key step of the purification procedure. The enzyme, responsible for the cleavage of the glycosidic bond of both S-adenosylhomocysteine and 5′-methylthioadenosine, was partially characterized. The apparent Km for 5′-methylthioadenosine is 0.4 microM, and that for S-adenosylhomocysteine is 4.3 microM. The maximal rate of cleavage of S-adenosylhomocysteine is approx. 40% of that of 5′-methylthioadenosine. Some 25 analogues of the two naturally occurring thioethers were studied as potential substrates or inhibitors of the enzyme. Except for the analogues modified in the 5′-position of the ribose moiety or the 2-position of the purine ring, none of the compounds tested was effective as a substrate. Moreover, 5′-methylthioformycin, 5′-chloroformycin, S-formycinylhomocysteine, 5′-methylthiotubercidin and S-tubercidinylhomocysteine were powerful inhibitors of the enzyme activity. The results obtained allow the hypothesis of a mechanism of enzymic catalysis requiring as a key step the protonation of N-7 of the purine ring.

scholarly journals Biosynthesized silver nanoparticles: Decoding their mechanism of action in Staphylococcus aureus and Escherichia coli

2018 ◽  
Vol 104 ◽  
pp. 87-93 ◽  
Author(s):  
Melisa A. Quinteros ◽  
Cano Aristizabal Viviana ◽  
Renné Onnainty ◽  
Verónica S. Mary ◽  
Martín G. Theumer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Silver Nanoparticles ◽  
Mechanism Of Action

Mechanism of Action of Nalidixic Acid on Escherichia coli VI. Cell-free Studies

1969 ◽  
Vol 97 (1) ◽  
pp. 230-236 ◽  
Author(s):  
James V. Boyle ◽  
Thomas M. Cook ◽  
William A. Goss
Keyword(s):  
Escherichia Coli ◽  
Nalidixic Acid ◽  
Mechanism Of Action
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