Inhibition of sulfur incorporation to transfer RNA by ultraviolet-A radiation in Escherichia coli. 2003

Oscar J Oppezzo, and Ramón A Pizarro
Departamento de Radiobiología, Comisión Nacional de Energía Atómica, Av. General Paz 1499, 1650 General San Martín, Buenos Aires, Argentina. oppezzo@cnea.gov.ar

tRNA sulfurtransferase activity was assayed in Escherichia coli cell extracts obtained from bacterial suspensions exposed to a sub-lethal dose of ultraviolet-A radiation (fluence 148 kJ m(-2)) imparted at a low fluence rate (41 W m(-2)). We found that the irradiation reduced the enzymatic activity to one fourth of the control value, indicating that ultraviolet-A exposure inhibits the synthesis of 4-thiouridine, the most abundant thionucleoside in E. coli tRNA. Changes in the tRNA content of 4-thiouridine and its derived photoproduct 5-(4'-pyrimidin 2'-one) cytosine were studied in bacteria growing under ultraviolet-A irradiation. In these conditions the accumulation of photoproduct was limited, and the kinetics of this process was non-coincident with disappearance of 4-thiouridine. The results, which are compatible with the fact that ultraviolet-A induces an inhibition of the 4-thiouridine synthesis, suggest that the effect of radiation on tRNA modification is relevant to tRNA photo-inactivation in growing bacteria.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D004926 Escherichia coli A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc. Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D012329 RNA, Bacterial Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis. Bacterial RNA
D012343 RNA, Transfer The small RNA molecules, 73-80 nucleotides long, that function during translation (TRANSLATION, GENETIC) to align AMINO ACIDS at the RIBOSOMES in a sequence determined by the mRNA (RNA, MESSENGER). There are about 30 different transfer RNAs. Each recognizes a specific CODON set on the mRNA through its own ANTICODON and as aminoacyl tRNAs (RNA, TRANSFER, AMINO ACYL), each carries a specific amino acid to the ribosome to add to the elongating peptide chains. Suppressor Transfer RNA,Transfer RNA,tRNA,RNA, Transfer, Suppressor,Transfer RNA, Suppressor,RNA, Suppressor Transfer
D013455 Sulfur An element that is a member of the chalcogen family. It has an atomic symbol S, atomic number 16, and atomic weight [32.059; 32.076]. It is found in the amino acids cysteine and methionine. Sulfur-16,Sulfur 16
D013466 Sulfurtransferases Enzymes which transfer sulfur atoms to various acceptor molecules. EC 2.8.1. Sulfurtransferase
D014466 Ultraviolet Rays That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants. Actinic Rays,Black Light, Ultraviolet,UV Light,UV Radiation,Ultra-Violet Rays,Ultraviolet Light,Ultraviolet Radiation,Actinic Ray,Light, UV,Light, Ultraviolet,Radiation, UV,Radiation, Ultraviolet,Ray, Actinic,Ray, Ultra-Violet,Ray, Ultraviolet,Ultra Violet Rays,Ultra-Violet Ray,Ultraviolet Black Light,Ultraviolet Black Lights,Ultraviolet Radiations,Ultraviolet Ray

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