Fungal Enzyme l-Lysine α-Oxidase Affects the Amino Acid Metabolism in the Brain and Decreases the Polyamine Level

The fungal glycoprotein l-lysine α-oxidase (LO) catalyzes the oxidative deamination of l-lysine (l-lys). LO may be internalized in the intestine and shows antitumor, antibacterial, and antiviral effects in vivo. The main mechanisms of its effects have been shown to be depletion of the essential amino acid l-lys and action of reactive oxidative species produced by the reaction. Here, we report that LO penetrates into the brain and is retained there for up to 48 h after intravenous injection, which might be explained by specific pharmacokinetics. LO actively intervenes in amino acid metabolism in the brain. The most significant impact of LO was towards amino acids, which are directly exposed to its action (l-lys, l-orn, l-arg). In addition, the enzyme significantly affected the redistribution of amino acids directly associated with the tricarboxylic acid (TCA) cycle (l-asp and l-glu). We discovered that the depletion of l-orn, the precursor of polyamines (PA), led to a significant and long-term decrease in the concentration of polyamines, which are responsible for regulation of many processes including cell proliferation. Thus, LO may be used to reduce levels of l-lys and PA in the brain.

Modulation of polyamine catabolism in pea seedlings by calcium during salinity stress

The relation of polyamine catabolism in the response of Pisum sativum to salinity stress was investigated. Pea seedlings were grown in increasing concentrations of Na⁺ or K⁺ or at different concentration ratios of these ions. We studied the effect of Ca²⁺ supplementation on plants exposed to salinity stress. The parameters measured in the roots and shoots of pea seedlings included biomass production, levels of Na⁺, K⁺, Ca²⁺ and polyamines and activity of enzymes of polyamine catabolism: diamine oxidase, aminoaldehyde dehydrogenase and peroxidases. Salinity induced increased polyamine levels and higher activity of enzymes participating in polyamine degradation. Supplementation of Ca²⁺ had a positive effect on biomass production and in most cases it stabilised both the polyamine level and the activity of the studied enzymes. Our results confirm the role of aminoaldehyde dehydrogenase and polyamine catabolism in defence mechanisms of pea plants under salinity stress.

Polyamines Are Essential in Embryo Implantation: Expression and Function of Polyamine-Related Genes in Mouse Uterus during Peri-Implantation Period

Polyamines are key regulators in cell growth and differentiation. It has been shown that ornithine decarboxylase (Odc) was essential for post-implantation embryo development, and overexpression of spermidine/spermine N1-acetyltransferase will lead to ovarian hypofunction and hypoplastic uteri. However, the expression and function of polyamine-related genes in mouse uterus during early pregnancy are still unknown. In this study we investigated the expression, regulation, and function of polyamine-related genes in mouse uterus during the peri-implantation period. Odc expression was strongly detected at implantation sites and stimulated by estrogen treatment. The expression of Odc antizyme 1 and spermidine/spermine N1-acetyltransferase was also highly shown at implantation sites and regulated by Odc or polyamine level in uterine cells. Embryo implantation was significantly inhibited by α-difluoromethylornithine, an Odc inhibitor. Moreover, the reduction of Odc activity caused by α-difluoromethylornithine treatment was compensated by the up-regulation of S-adenosylmethionine decarboxylase gene expression. Collectively, our results indicated that the coordinated expression of uterine polyamine-related genes may be important for embryo implantation.