PMID: 7028566Jan 1, 1981Paper

Escherichia coli K-12 mutants for the thymidine phosphorylase structural gene that retain the anabolic function of the enzyme

Genetika
N D Moskaleva, V V Sukhodolets

Abstract

From the Escherichia coli thymine auxotroph carrying a constitutive mutation for deo-enzymes (thy deoR) mutants (tpp38, tpp39 and tpp40) for thymidine phosphorylase (catalyzing a conversion of thymine to thymidine) were isolated via selection for a low thymine requirement. In the thy deoR+ genome these mutations led to inability of bacteria to use thymidine as the sole carbon source for growth, though the ability to utilize thymine was retained at the level comparable to that of thy deoR+ tpp+ bacteria. In the thy deoR genome mutations obtained led to a more efficient utilization of thymine in comparison with the thy deoR tpp++ strain. At the same time, the thymidine phosphorylase activity, as determined by a degradation of thymidine in bacterial extracts was lower in thy deoR strains carrying tpp38, tpp39 and tpp40 by factors 5,25 and 22, respectively, in comparison with the thy deoR tpp+ strain. The mutations tpp38, 39, 40 were localized in the distal part of the tpp structural gene (tpp39 and tpp40 being in the extreme distal position), whereas the earlier described tpp-leaky mutants incapable of using exogenous thymine for growth were mapped in the extreme proximal part of the tpp gene (Sukhodolets et al., 1971). It is prop...Continue Reading

Related Concepts

Trending Feeds

COVID-19

Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Blastomycosis

Blastomycosis fungal infections spread through inhaling Blastomyces dermatitidis spores. Discover the latest research on blastomycosis fungal infections here.

Nuclear Pore Complex in ALS/FTD

Alterations in nucleocytoplasmic transport, controlled by the nuclear pore complex, may be involved in the pathomechanism underlying multiple neurodegenerative diseases including Amyotrophic Lateral Sclerosis and Frontotemporal Dementia. Here is the latest research on the nuclear pore complex in ALS and FTD.

Applications of Molecular Barcoding

The concept of molecular barcoding is that each original DNA or RNA molecule is attached to a unique sequence barcode. Sequence reads having different barcodes represent different original molecules, while sequence reads having the same barcode are results of PCR duplication from one original molecule. Discover the latest research on molecular barcoding here.

Chronic Fatigue Syndrome

Chronic fatigue syndrome is a disease characterized by unexplained disabling fatigue; the pathology of which is incompletely understood. Discover the latest research on chronic fatigue syndrome here.

Evolution of Pluripotency

Pluripotency refers to the ability of a cell to develop into three primary germ cell layers of the embryo. This feed focuses on the mechanisms that underlie the evolution of pluripotency. Here is the latest research.

Position Effect Variegation

Position Effect Variagation occurs when a gene is inactivated due to its positioning near heterochromatic regions within a chromosome. Discover the latest research on Position Effect Variagation here.

STING Receptor Agonists

Stimulator of IFN genes (STING) are a group of transmembrane proteins that are involved in the induction of type I interferon that is important in the innate immune response. The stimulation of STING has been an active area of research in the treatment of cancer and infectious diseases. Here is the latest research on STING receptor agonists.

Microbicide

Microbicides are products that can be applied to vaginal or rectal mucosal surfaces with the goal of preventing, or at least significantly reducing, the transmission of sexually transmitted infections. Here is the latest research on microbicides.