s-adenosyl-3-methylthiopropylamine and 5--methylthioadenosine

The Saccharomyces cerevisiae SPE3 gene, coding for spermidine synthase, was cloned, sequenced, and localized on the right arm of chromosome XVI. The deduced amino acid sequence has a high similarity to mammalian spermidine synthases, and has putative S-adenosylmethionine binding motifs. To investigate the effect of total loss of the SPE3 gene, we constructed a null mutant of this gene, spe3delta, which has no spermidine synthase activity and has an absolute requirement for spermidine or spermine for the growth. This requirement is satisfied by a very low concentration of spermidine (10(-8) M) or a higher concentration of spermine (10(-6) M).

Topics: Amino Acid Sequence; Chromosome Mapping; Cloning, Molecular; Conserved Sequence; Deoxyadenosines; Genes, Fungal; Molecular Sequence Data; Mutation; S-Adenosylmethionine; Saccharomyces cerevisiae; Sequence Analysis; Sequence Homology, Amino Acid; Spermidine; Spermidine Synthase; Thionucleosides

Experiments were conducted to determine the effects of dietary supplements of amino acid precursors of polyamines on amino acid metabolism in the rat in order to better understand comparative aspects of polyamine metabolism. Rats were fed isonitrogenous combinations of methionine, ornithine, arginine and 2-difluoromethylornithine in casein-based diets. It was observed that hepatic concentrations of methionine, 5'-deoxy-5'-methylthioadenosine and decarboxylated S-adenosylmethionine were more easily influenced by diet than were arginine and metabolites. It was concluded that rats may be more refractory to exogenous polyamine precursor amino acids than are chicks because of the presence of a functional urea cycle.

Topics: Adenosine; Amino Acids; Animals; Arginine; Biogenic Polyamines; Deoxyadenosines; Diet; Liver; Male; Methionine; Muscles; Ornithine; Rats; Rats, Inbred Strains; RNA, Transfer, Amino Acid-Specific; S-Adenosylmethionine; Thionucleosides

Topics: Adenine; Adenosine; Animals; Chromatography, High Pressure Liquid; Deoxyadenosines; Male; Rats; Rats, Inbred Strains; S-Adenosylhomocysteine; S-Adenosylmethionine; Thionucleosides