Specificity and Efficiency of Thymidine Incorporation in Escherichia coli Lacking Thymidine Phosphorylase
AUTOR(ES)
Fangman, Walton L.
RESUMO
A mutant of Escherichia coli lacking the catabolic enzyme thymidine phosphorylase readily incorporates exogenous thymidine into deoxyribonucleic acid (DNA) even when provided at concentrations as low as 0.2 μg/ml. Incorporation by this prototrophic strain occurs specifically into DNA, since, with radioactively labeled thymidine, (i) more than 98% is incorporated into alkali-stable material, (ii) at least 90% is recovered as thymine after brief formic acid hydrolysis, and (iii) at least 90% is incorporated into material with the buoyant density of DNA. During growth in medium containing thymidine, the bacteria obtain approximately half of their DNA thymines from the exogenous thymidine and half from endogenous synthesis. The thymines and cytosines of DNA can be simultaneously and specifically labeled by thymidine-2-14C and uridine-5-3H, respectively. The mutant, which does not degrade thymidine, retains the ability to degrade the thymidine analogue 5-bromodeoxyuridine.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=250081Documentos Relacionados
- Thymidine and Thymine Incorporation into Deoxyribonucleic Acid: Inhibition and Repression by Uridine of Thymidine Phosphorylase of Escherichia coli
- Efficiency of Thymidine Incorporation in Escherichia coli B/r as a Function of Growth Rate
- Genetic mapping of a mutation in Escherichia coli showing reduced activity of thymidine phosphorylase.
- Effect of Adenosine and Deoxyadenosine on the Incorporation and Breakdown of Thymidine in Escherichia coli K-12
- Residual Thymidine Incorporation in the Presence of Chloramphenicol in Synchronous Cultures of Escherichia coli B/r
