Biosynthesis of diphthamide in the yeast Saccharomyces cerevisiae

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1985

OSTI ID:6108741

Chen, J Y.C.

Inactivation of EF-2 by diphtheria toxin requires the presence of a posttranslationally synthesized amino acid residue, diphthamide. The present work was undertaken to study the biosynthetic mechanism of diphthamide synthesis in the yeast Saccharomyces cerevisiae in order to gain better understanding of the biological roles of this unique amino acid residue. Thirty-one haploid ADP-ribosylation-negative mutants, comprising 5 complementation groups, were obtained. One of these mutants contains a toxin-resistant form of EF-2 which can be converted to a toxin-sensitive form through the methylation reaction catalyzed by a S-AdoMet:EF-2 methyltransferase enzyme which is present in other yeast strains. The (/sup 3/He)methylated residue in the EF-2 modified by the methyltransferase in the presence of S-Ado-L-(/sup 3/H-methyl)-Met has been analyzed chromatographically following both acid and enzymatic hydrolysis. At the conclusion of the reaction, all of the radiolabel was recovered as diphthine (the unamidated form of diphthamide). The authors conclude that the S-AdoMet:EF-2-methyltransferase is specific for the addition of at least the last two of the three methyl groups present in diphthine.

• Research Organization: Minnesota Univ., Minneapolis (USA)
• OSTI ID: 6108741
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AMIDES
BIOSYNTHESIS
TRANSFERASES
BIOCHEMISTRY
AMINO ACIDS
SACCHAROMYCES CEREVISIAE
TOXINS
TRITIUM COMPOUNDS
ANTIGENS
CARBOXYLIC ACIDS
CHEMISTRY
ENZYMES
FUNGI
LABELLED COMPOUNDS
MATERIALS
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PLANTS
SACCHAROMYCES
SYNTHESIS
TOXIC MATERIALS
YEASTS
550201* - Biochemistry- Tracer Techniques