tRNA modified bases and oxidative stress in Salmonella typhimurium

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5513695

Kramer, G F

The mechanisms of toxicity of two different environmental stresses have been characterized in Salmonella typhimurium. The toxicity of near-UV (NUV) light (300-400 nm) appeared to be mediated by oxidative mechanisms. The overproduction of NUV-absorbing proteins sensitized the cells to killing by NUV. Selenium also appeared to be toxic to S. typhimurium by oxidative mechanisms. At low concentrations, the main target for this toxicity appeared to be intracellular thiols. At higher concentrations, selenite toxicity appeared to have been mediated by oxygen radicals which we have shown to be produced by the reactions of selenite with sulfhydryl groups. Such radicals may also have been involved in the selenite mutagenicity we have observed in S. typhimurium. The function of two different modified bases with respect to such oxidative stress has been characterized. The isolation of mutants lacking these bases has facilitated this investigation. S. typhimurium contained a single seleno-modified base, 5-methylaminomethyl-2-selenouridine (mnm{sup 5}Se{sup 2}U). Mutants which were unable to incorporate selenium into their tRNA (selA) were isolated based on a pleiotropic defect in selenium metabolism.

• Research Organization: California Univ., Berkeley, CA (USA)
• OSTI ID: 5513695
• Country of Publication: United States
• Language: English

Related Subjects

560130* -- Radiation Effects on Microorganisms
560300 -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACTERIA
BIOLOGICAL STRESS
CELL KILLING
ELECTROMAGNETIC RADIATION
ELEMENTS
METABOLISM
MICROORGANISMS
MUTATIONS
RADIATIONS
RADICALS
SALMONELLA
SALMONELLA TYPHIMURIUM
SELENIUM
SEMIMETALS
TOXICITY
ULTRAVIOLET RADIATION