Isolation and characterization of a selenium metabolism mutant of Salmonella typhimurium

Journal Article · Mon Feb 01 00:00:00 EST 1988 · J. Bacteriol.; (United States)

OSTI ID:5317644

Kramer, G F; Ames, B N

Selenium is a constituent in Escherichia coli of the anaerobic enzyme formate dehydrogenase in the form of selenocysteine. Selenium is also present in the tRNA of E. coli in the modified base 5-methylaminomethyl-2-selenouracil (mnm/sup 5/Se/sup 2/U). The pathways of bacterial selenium metabolism are largely uncharacterized, and it is unclear whether nonspecific reactions in the sulfur metabolic pathways may be involved. We demonstrated that sulfur metabolic pathway mutants retain a wild-type pattern of selenium incorporation, indicating that selenite (SeO/sub 3//sup 2 -/) is metabolized entirely via selenium-specific pathways. To investigate the function of mnm/sup 5/Se/sup 2/U, we isolated a mutant which is unable to incorporate selenium into tRNA. This strain was obtained by isolating mutants lacking formate dehydrogenase activity and then screening for the inability to metabolize selenium. This phenotype is the result of a recessive mutation which appears to map in the general region of 21 min on the Salmonella typhimurium chromosome. We showed that the absence of selenium incorporation into suppressor tRNA reduces the efficiency of suppression of nonsense codons in certain contexts and when wobble base pairing is required. Thus, one function of mnm/sup 5/Se/sup 2/U in tRNA may be in codon-anticodon interactions.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 5317644
• Journal Information: J. Bacteriol.; (United States), Vol. 170:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
SALMONELLA TYPHIMURIUM
METABOLISM
SELENIUM
BIOLOGICAL FUNCTIONS
BIOLOGICAL PATHWAYS
CYSTEINE
FORMATES
GENETIC MAPPING
MUTANTS
OXIDOREDUCTASES
TRANSFER RNA
AMINO ACIDS
BACTERIA
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
ELEMENTS
ENZYMES
FUNCTIONS
MAPPING
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
RNA
SALMONELLA
SEMIMETALS
THIOLS
550200* - Biochemistry
560300 - Chemicals Metabolism & Toxicology