Down regulation of S-adenosyl-L-methionine decarboxylase activity of Trypanosoma brucei during transition from long slender to short stumpy-like forms in axenic culture. 1996

P M Selzer, and F Hesse, and B Hamm-Kunzelmann, and K Muhlstadt, and H Echner, and M Duszenko
Physiologisch-chemisches Institut der Universitat, Tubingen, Germany.

Long slender trypanosomes, isolated from infected mouse blood or from cryopreserved stabilates, respectively, were unable to grow in conditioned media (cMEM), prepared from the declining phase of axenic bloodstream form cultures. Additionally, mixtures of fresh medium and cMEM led to decreased growth rates and, in accordance to the amount of cMEM used, to a decreased S-adenosyl-L-methionine decarboxylase (Ado-MetDC; E.C. 4.1.1.50) activity. Since addition of polyamines could not overcome the process of transition from dividing to non-dividing cells and the intracellular S-adenosyl-L-methionine (AdoMet), ornithine and putrescine concentrations seemed unaltered during the course of cultivation, we questioned if polyamine metabolism is involved in this transition process. Activities of two key enzymes of polyamine metabolism, AdoMetDC and ornithine decarboxylase (ODC; E.C. 4.1.1.17) were therefore monitored during different growth stages. Our results revealed a specific activity of 44 pmol min-1 mg protein-1 for AdoMetDC and a KM of 10 mu M for AdoMet. Methylglyoxal bis(guanylhydrazone) showed a Ki of 6 mu M. The constant activity of the enzyme during a 7 h time-course in the presence of cycloheximide indicates a t1/2 of more than 7 h for the trypanosomal enzyme. Enzyme activity in trypanosomes isolated from infected laboratory animals and from logarithmic phase bloodstream or procyclic form cultures was high according to a high dividing rate, whereas enzyme activity in parasites isolated from the stationary phase of bloodstream from culture was negligible. In these cultures, AdoMetDC activity decreased with a t1/2 of 7 h during transition from long slender to short stumpy-like forms as soon as the stationary phase was reached. ODC activity was high (approximately 300 pmol min-1 mg protein-1) in dividing trypanosomes isolated from infected animals as well as from logarithmic phase bloodstream or procyclic form cultures and decreased also during transition with a t1/2 of 10 h.

UI MeSH Term Description Entries
D009955 Ornithine Decarboxylase A pyridoxal-phosphate protein, believed to be the rate-limiting compound in the biosynthesis of polyamines. It catalyzes the decarboxylation of ornithine to form putrescine, which is then linked to a propylamine moiety of decarboxylated S-adenosylmethionine to form spermidine. Ornithine Carboxy-lyase,Carboxy-lyase, Ornithine,Decarboxylase, Ornithine,Ornithine Carboxy lyase
D002454 Cell Differentiation Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs. Differentiation, Cell,Cell Differentiations,Differentiations, Cell
D005856 Germ-Free Life Animals not contaminated by or associated with any foreign organisms. Axenic Animals,Gnotobiotics,Germfree Life,Animal, Axenic,Animals, Axenic,Axenic Animal,Germ Free Life,Gnotobiotic,Life, Germ-Free,Life, Germfree
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012437 Adenosylmethionine Decarboxylase An enzyme that catalyzes the decarboxylation of S-adenosyl-L-methionine to yield 5'-deoxy-(5'-),3-aminopropyl-(1), methylsulfonium salt. It is one of the enzymes responsible for the synthesis of spermidine from putrescine. EC 4.1.1.50. S-Adenosylmethionine Decarboxylase,Decarboxylase, Adenosylmethionine,Decarboxylase, S-Adenosylmethionine,S Adenosylmethionine Decarboxylase
D014176 Protein Biosynthesis The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS. Genetic Translation,Peptide Biosynthesis, Ribosomal,Protein Translation,Translation, Genetic,Protein Biosynthesis, Ribosomal,Protein Synthesis, Ribosomal,Ribosomal Peptide Biosynthesis,mRNA Translation,Biosynthesis, Protein,Biosynthesis, Ribosomal Peptide,Biosynthesis, Ribosomal Protein,Genetic Translations,Ribosomal Protein Biosynthesis,Ribosomal Protein Synthesis,Synthesis, Ribosomal Protein,Translation, Protein,Translation, mRNA,mRNA Translations
D014346 Trypanosoma brucei brucei A hemoflagellate subspecies of parasitic protozoa that causes nagana in domestic and game animals in Africa. It apparently does not infect humans. It is transmitted by bites of tsetse flies (Glossina). Trypanosoma brucei,Trypanosoma brucei bruceus,Trypanosoma bruceus,brucei brucei, Trypanosoma,brucei, Trypanosoma brucei,bruceus, Trypanosoma,bruceus, Trypanosoma brucei
D015536 Down-Regulation A negative regulatory effect on physiological processes at the molecular, cellular, or systemic level. At the molecular level, the major regulatory sites include membrane receptors, genes (GENE EXPRESSION REGULATION), mRNAs (RNA, MESSENGER), and proteins. Receptor Down-Regulation,Down-Regulation (Physiology),Downregulation,Down Regulation,Down-Regulation, Receptor
D016015 Logistic Models Statistical models which describe the relationship between a qualitative dependent variable (that is, one which can take only certain discrete values, such as the presence or absence of a disease) and an independent variable. A common application is in epidemiology for estimating an individual's risk (probability of a disease) as a function of a given risk factor. Logistic Regression,Logit Models,Models, Logistic,Logistic Model,Logistic Regressions,Logit Model,Model, Logistic,Model, Logit,Models, Logit,Regression, Logistic,Regressions, Logistic
D046508 Culture Techniques Methods of maintaining or growing biological materials in controlled laboratory conditions. These include the cultures of CELLS; TISSUES; organs; or embryo in vitro. Both animal and plant tissues may be cultured by a variety of methods. Cultures may derive from normal or abnormal tissues, and consist of a single cell type or mixed cell types. Culture Technique,Technique, Culture,Techniques, Culture

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