O sub 2 -dependent methionine auxotrophy in Cu,Zn superoxide dismutase-deficient mutants of Saccharomyces cerevisiae

Journal Article · Sun Apr 01 00:00:00 EST 1990 · Journal of Bacteriology; (USA)

OSTI ID:7005118

Chang, E C; Kosman, D J ^[1]

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1. State Univ. of New York, Buffalo (USA)

Mutant strains of the yeast Saccharomyces cerevisiae which lack functional Cu,Zn superoxide dismutase (SOD-1) do not grow aerobically unless supplemented with methionine. The molecular basis of this O2-dependent auxotrophy in one of the mutants, Dscd1-1C, has been investigated. Sulfate supported anaerobic but not aerobic mutant growth. On the other hand, cysteine and homocysteine supported aerobic growth while serine, O-acetylserine, and homoserine did not, indicating that the interconversion of cysteine and methionine (and homocysteine) was not impaired. Thiosulfate (S2O3)2- and sulfide (S2-) also supported aerobic growth; the activities of thiosulfate reductase and sulfhydrylase in the aerobic mutant strain were at wild-type levels. Although the levels of SO4(2-) and adenosine-5'-sulfate (the first intermediate in the SO4(2-) assimilation pathway) were elevated in the aerobically incubated mutant strain, this condition could be attributed to a decrease in protein synthesis caused by the de facto sulfur starvation and not to a block in the pathway. Therefore, the activation of SO4(2-) (to form 3'-phosphoadenosine-5'-phosphosulfate) appeared to be O2 tolerant. Sulfite reductase activity and substrate concentrations (( NADPH) and (SO3(2-))) were not significantly different in aerobically grown mutant cultures and anaerobic cultures, indicating that SOD-1- mutant strains could reductively assimilate sulfur oxides. However, the mutant strain exhibited an O2-dependent sensitivity to SO3(2-) concentrations of less than 50 microM not exhibited by any SOD-1+ strain or by SOD-1- strains supplemented with a cytosolic O2(-)-scavenging activity.

• OSTI ID: 7005118
• Journal Information: Journal of Bacteriology; (USA), Vol. 172:4; ISSN 0021-9193
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
SACCHAROMYCES CEREVISIAE
GROWTH
SULFATES
BIOLOGICAL EFFECTS
SULFIDES
SULFITES
SUPEROXIDE DISMUTASE
BIOLOGICAL FUNCTIONS
AEROBIC CONDITIONS
ANAEROBIC CONDITIONS
BIOLOGICAL PATHWAYS
CYSTEINE
ENZYME ACTIVITY
METHIONINE
MUTANTS
OXIDOREDUCTASES
OXYGEN
SERINE
AMINO ACIDS
CARBOXYLIC ACIDS
CHALCOGENIDES
DRUGS
ELEMENTS
ENZYMES
EUMYCOTA
FUNCTIONS
FUNGI
HYDROXY ACIDS
LIPOTROPIC FACTORS
MICROORGANISMS
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
PLANTS
SACCHAROMYCES
SULFUR COMPOUNDS
THIOLS
YEASTS
560300* - Chemicals Metabolism & Toxicology