Isolation and characterization of a selenium metabolism mutant of Salmonella typhimurium

Journal Article · Mon Feb 01 04:00:00 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), Journal Name: J. Bacteriol.; (United States) Vol. 170:2; ISSN JOBAA
• Country of Publication: United States
• Language: English

Related Subjects

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