Effect of various polyamine analogs on in vitro polypeptide synthesis

Differential expression of polyamine biosynthetic pathways in skin lesions and in plasma reveals distinct profiles in diffuse cutaneous leishmaniasis

Tegumentary leishmaniasis (TL) is a parasitic disease that can result in wide spectrum clinical manifestations. It is necessary to understand host and parasite determinants of clinical outcomes to identify novel therapeutic targets. Previous studies have indicated that the polyamine biosynthetic pathway is critical for Leishmania growth and survival. Despite its importance, expression of the such pathway has not been previously investigated in TL patients. We performed an exploratory analysis employing Systems Biology tools to compare circulating polyamines and amino acid concentration as well as polyamine pathway gene expression in cutaneous lesions patients presenting with distinct TL disease presentations. Diffuse cutaneous leishmaniasis (DCL) was associated with higher concentrations of amino acids, polyamines and its substrate transporters than mucosal cutaneous leishmaniasis or localized cutaneous leishmaniasis. In addition, the RNA expression of polyamine-related genes of patients lesions from two separate cohorts demonstrated that differential activation of this pathway is associated with parasite loads and able to discriminate the clinical spectrum of TL. Taken together, our findings highlight a new aspect of DCL immunopathogenesis indicating that the polyamine pathway may be explored as a novel therapeutic target to control disease burden.

Effects of polyamines on proliferation and IgM productivity of human-human hybridoma, HB4C5 cells

Immunoglobulin production stimulating activity of polyamines was investigated. Spermidine, thermine and triethylenetetraamine (TETA) stimulated IgM production of human-human hybridoma, HB4C5 cells under serum-free condition. IgM production of HB4C5 cells was accelerated 5.9-, 5.3-, and 3.7-fold by spermidine at 4.5 mM, thermine at 2 mM and TETA at 2.5 mM, respectively. However, putrescine did not enhance IgM production. Spermidine enhanced IgM productivity of the hybridoma cells in spite of its growth suppression activity. TETA also inhibited cell proliferation and the effect on the acceleration of IgM productivity disappeared during 5 days because of its cytotoxicity. On the other hand, thermine facilitated IgM productivity of the hybridoma cells without growth suppression. The laser confocal microscopic analysis revealed that IgM content inside HB4C5 cells was increased by thermine. This result suggests that thermine facilitates IgM synthesis in hybridoma cells.

Decrease in polyamines with aging and their ingestion from food and drink

Changes in polyamine levels during aging were measured in 3-, 10- and 26-week-old female mice. The level of polyamines in pancreas, brain, and uterus was maintained during these periods. The level of spermidine slightly decreased in intestine, and decreased significantly in thymus, spleen, ovary, liver, stomach, lung, kidney, heart and muscle during these periods. In skin, the level of spermidine was maximal in 10-week-old mice and markedly reduced in 26-week-old mice. The results suggest that maintenance of polyamine levels may play important roles in the function of the pancreas, brain and uterus in 3- to 26-week-old mice. We next looked for polyamine-rich food materials as a dietary source of polyamines. Foods found to be rich in polyamines included wheat germ, rice bran, black rice, Philippine mango, green pepper, Japanese pumpkin, nuts, fermented pickles, pond smelt, turban shell viscera, whelk viscera, salted salmon roe, salted cod roe, beef intestine (boiled) and liver of eel, beef, pork and chicken; and, as previously reported, soybean, fermented soybean (natto), mushrooms, orange and green tea leaf. These results offer useful information when it becomes necessary to ingest polyamines from food.

N1-aminopropylagmatine, a new polyamine produced as a key intermediate in polyamine biosynthesis of an extreme thermophile, Thermus thermophilus

In the extreme thermophile Thermus thermophilus, a disruption mutant of a gene homologous to speB (coding for agmatinase = agmatine ureohydrolase) accumulated N1-aminopropylagmatine (N8-amidino-1,8-diamino-4-azaoctane, N8-amidinospermidine), a new compound, whereas all other polyamines produced by the wild-type strain were absent from the cells. Double disruption of speB and speE (polyamine aminopropyltransferase) resulted in the disappearance of N1-aminopropylagmatine and the accumulation of agmatine. These results suggested the following. 1) N1-Aminopropylagmatine is produced from agmatine by the action of an enzyme coded by speE. 2) N1-Aminopropylagmatine is a metabolic intermediate in the biosynthesis of unique polyamines found in the thermophile. 3) N1-Aminopropylagmatine is a substrate of the SpeB homolog. They further suggest a new biosynthetic pathway in T. thermophilus, by which polyamines are formed from agmatine via N1-aminopropylagmatine. To confirm our speculation, we purified the expression product of the speB homolog and confirmed that the enzyme hydrolyzes N1-aminopropylagmatine to spermidine but does not act on agmatine.

Excretion of Putrescine and Spermidine by the Protein Encoded by YKL174c (TPO5) in Saccharomyces cerevisiae

The properties of the protein encoded by YKL174c (TPO5) were studied. It was found that TPO5 excretes putrescine effectively and spermidine less effectively. Gamma-aminobutyric acid slightly inhibited the excretion of putrescine, but basic amino acids did not affect excretion, suggesting that TPO5 preferentially recognizes polyamines. Accordingly, yeast cells transformed with the plasmid encoding YKL174c (TPO5) were resistant to toxicity caused by 120 mm putrescine or by 3 mm spermidine, and a mutant with a disrupted YKL174c (TPO5) gene was sensitive to toxicity by 90 mm putrescine. The growth of this mutant was faster than that of the wild-type strain. In parallel, there was an increase in putrescine and spermidine content of the YKL174c (TPO5) mutant compared with wild-type. It is noted that TPO5 functions as a suppressor of cell growth by excreting polyamines. The level of YKL174c (TPO5) mRNA was increased by the addition of polyamines to the medium. The degree of induction of the mRNA was spermine > spermidine > putrescine. The subcellular localization of TPO5 was determined by immunostaining of hemagglutinin-tagged TPO5, and it was found on Golgi or post-Golgi secretory vesicles. Excretion of putrescine and spermidine by TPO5 was reduced in cells that have mutations in the secretory or endocytic pathways, indicating that both processes are involved in the excretion of polyamines.

Excretion and uptake of cadaverine by CadB and its physiological functions in Escherichia coli

The functions of the putative cadaverine transport protein CadB were studied in Escherichia coli. CadB had both cadaverine uptake activity, dependent on proton motive force, and cadaverine excretion activity, acting as a cadaverine-lysine antiporter. The Km values for uptake and excretion of cadaverine were 20.8 and 303 microM respectively. Both cadaverine uptake and cadaverine-lysine antiporter activities of CadB were functional in cells. Cell growth of a polyamine-requiring mutant was stimulated slightly at neutral pH by the cadaverine uptake activity and greatly at acidic pH by the cadaverine-lysine antiporter activity. At acidic pH, the operon containing cadB and cadA, encoding lysine decarboxylase, was induced in the presence of lysine. This caused neutralization of the extracellular medium and made possible the production of CO(2) and cadaverine and aminopropylcadaverine instead of putrescine and spermidine. The induction of the cadBA operon also generated a proton motive force. When the cadBA operon was not induced, the expression of the speF-potE operon, encoding inducible ornithine decarboxylase and a putrescine-ornithine antiporter, was increased. The results indicate that the cadBA operon plays important roles in cellular regulation at acidic pH.

Effects of polyamine analogs on the extent and fidelity of in vitro polypeptide synthesis

A series of polyamine analogs has been examined for their ability to support protein synthesis in an in vitro rabbit reticulocyte translation system. Diamines were found to stimulate protein synthesis to the greatest extent (8-12 fold). Triamines, tetraamines and pentaamines only stimulated 2-4 fold under these conditions although much lower concentrations were required. At elevated temperatures (45 degrees C), diamines were somewhat more active than at lower temperature but activity of longer chain polyamines was elevated very significantly. Polyamines with terminal benzyl or smaller alkyl groups had diminished activity. It is concluded that both charge and charge distribution determine the ability of polyamines to stimulate translation. Fidelity studies identified two classes of polyamines: those which are able to lower the optimal Mg2+ concentration required for amino acid misincorporation while not affecting extent of misincorporation relative to Mg2+ alone, and those which are sparing for Mg2+ and also stimulate extent of misincorporation.

Effect of norspermidine and its related triamines on the cell-free polyphenylalanine synthesizing system from Vibrio parahaemolyticus

The effect of norspermidine and its structurally related triamines on the cell-free polyphenylalanine synthesizing system from Vibrio parahaemolyticus was examined in connection with the requirement of the system for monovalent cation. In the absence of norspermidine, the maximal incorporation of [14C]phenylalanine into hot trichloroacetic acid insoluble material was observed under ionic conditions of 12 mM Mg2+ and 50 mM NH4+. K+ could partially substitute for NH4+, but Na+ could not. The addition of norspermidine to the polyphenylalanine synthetic reaction mixture not only lowered the optimal Mg2+ concentration, but it also stimulated the polyphenylalanine synthesis up to 2-fold with no significant increase in misincorporation of [14C]leucine. Other triamines having one or two methylene chains more than norspermidine were also effective in eliciting these effects. Furthermore, Na+ could not support the polyphenylalanine synthesis even in the presence of norspermidine and, on the contrary, inhibited the polyphenylalanine synthesis induced by NH4+ regardless of whether norspermidine was present or not. These findings are discussed in comparison with the properties of other bacterial cell-free systems.