bims-polyam 2022-12-11 papers

Issue of 2022–12–11
five papers selected by
Sebastian J. Hofer, University of Graz

mBio. 2022 Dec 07. e0269822

Cation Homeostasis: Coordinate Regulation of Polyamine and Magnesium Levels in Salmonella.

Yumi Iwadate, Yekaterina A Golubeva, James M Slauch.

Polyamines are organic cations that are important in all domains of life. Here, we show that in Salmonella, polyamine levels and Mg2+ levels are coordinately regulated and that this regulation is critical for viability under both low and high concentrations of polyamines. Upon Mg2+ starvation, polyamine synthesis is induced, as is the production of the high-affinity Mg2+ transporters MgtA and MgtB. Either polyamine synthesis or Mg2+ transport is required to maintain viability. Mutants lacking the polyamine exporter PaeA, the expression of which is induced by PhoPQ in response to low Mg2+, lose viability in the stationary phase. This lethality is suppressed by blocking either polyamine synthesis or Mg2+ transport, suggesting that once Mg2+ levels are reestablished, the excess polyamines must be excreted. Thus, it is the relative levels of both Mg2+ and polyamines that are regulated to maintain viability. Indeed, sensitivity to high concentrations of polyamines is proportional to the Mg2+ levels in the medium. These results are recapitulated during infection. Polyamine synthesis mutants are attenuated in a mouse model of systemic infection, as are strains lacking the MgtB Mg2+ transporter. The loss of MgtB in the synthesis mutant background confers a synthetic phenotype, confirming that Mg2+ and polyamines are required for the same process(es). Mutants lacking PaeA are also attenuated, but deleting paeA has no phenotype in a polyamine synthesis mutant background. These data support the idea that the cell coordinately controls both the polyamine and Mg2+ concentrations to maintain overall cation homeostasis, which is critical for survival in the macrophage phagosome. IMPORTANCE Polyamines are organic cations that are important in all life forms and are essential in plants and animals. However, their physiological functions and regulation remain poorly understood. We show that polyamines are critical for the adaptation of Salmonella to low Mg2+ conditions, including those found in the macrophage phagosome. Polyamines are synthesized upon low Mg2+ stress and partially replace Mg2+ until cytoplasmic Mg2+ levels are restored. Indeed, it is the sum of Mg2+ and polyamines in the cell that is critical for viability. While Mg2+ and polyamines compensate for one another, too little of both or too much of both is lethal. After cytoplasmic Mg2+ levels are reestablished, polyamines must be exported to avoid the toxic effects of excess divalent cations.

Keywords: Salmonella; magnesium; polyamines

DOI: https://doi.org/10.1128/mbio.02698-22

J Therm Biol. 2022 Dec;pii: S0306-4565(22)00167-X. [Epub ahead of print]110 103353

Spermidine alleviates heat shock and promotes the growth of Bombyx mori.

Anugata Lima, Brinda Goda Lakshmi Didugu, Alekhya Rani Chunduri, Resma Rajan, Anitha Mamillapalli.

Silkworms have limited ability to regulate their body temperature upon exposure to varying atmospheric temperatures. Environmental changes, such as global warming, adversely affect silkworm viability. Spermidine, a polyamine, protects various organisms against heat stress. This study aimed to evaluate the effect of spermidine on the thermotolerance of Bombyx mori larvae. 5th instar Bombyx mori larvae were divided into the control and spermidine groups and reared at 28 ± 1 °C and 80%-85% relative humidity. To induce heat stress, the larvae were exposed to various temperatures 32 °C, 36 °C, and 40 °C for 1 h on day 5 and subsequently allowed to recover at 28 ± 1 °C. Growth characteristics were evaluated by examining larval viability and quantifying proteins and carbohydrates. The thermotolerance of the spermidine group was higher than that of the control group at 40 °C heat stress conditions. The spermidine feeding increased the protein content and reduced the carbohydrate content significantly under heat stress condition. For the first time, this study demonstrated that spermidine alleviated thermal stress by enhancing the nutritional indices and antioxidant potential of the Bombyx mori larvae. A significant increase in economic properties was observed in spermidine fed groups. Thus, foliar feeding of spermidine to B. mori larvae markedly improved silkworm thermotolerance.

Keywords: Antioxidant potential; Bombyx mori; Heat stress; Nutrition indices; Spermidine

DOI: https://doi.org/10.1016/j.jtherbio.2022.103353

J Sep Sci. 2022 Dec 08.

Determination of polyamines in urine via electrospun nanofibers based solid-phase extraction coupled with GC-MS and application to gastric cancer patients.

Li Xie, Weilin Chen, Qing Shu, Wei Xie, Linxiao Bian, Guozhe Deng, Xuejun Kang, Weihong Ge.

The simultaneous determination of polyamines and their metabolites in urine samples was achieved by GC-MS in the selected ion monitoring mode. After conjugating with the ion-pair reagent bis-2-ethylhexylphosphate in the aqueous phase, the polyamines in the samples were extracted with polystyrene nanofiber-based packed-fiber solid-phase extraction followed by a derivatization step using pentafluoropropionyl anhydride. With optimal conditions, all analytes were separated well. For analytes of putrescine, cadaverine, N-acetylputrescine and N-acetylcadaverine, the linearity was good in the range of 0.05-500 μmol/L (R2 ≥ 0.993). While for spermidine, spermine, acetylspermidine, N8 -acetylspermidine, and N-acetylspermine, the linearity was good in the range of 0.5-500 μmol/L (R2 ≥ 0.990). The recoveries of three spiked concentrations (0.5, 5, 300 μmol/L) were 85.6-108.4%, and RSDs for intra- and inter-day were in the range of 2.9-13.4% and 4.5-15.1%, respectively. The method was successfully applied to the analysis of urine samples of gastric cancer patients. The results showed that the levels of most polyamines and N-acetylated polyamines from the patient group were significantly higher than those from the control group. The altered concentrations of the above-mentioned metabolites suggest their role in the pathogenesis of gastric cancer, and they should be further evaluated as potential markers of gastric cancer. This article is protected by copyright. All rights reserved.

Keywords: Gastric Cancer; Ion-pairing; Polyamines; Polystyrene nanofibers; Solid-phase extraction

DOI: https://doi.org/10.1002/jssc.202200629

J Anim Sci Biotechnol. 2022 Dec 08. 13(1): 134

Dietary supplementation with 0.4% L-arginine between days 14 and 30 of gestation enhances NO and polyamine syntheses and water transport in porcine placentae.

Cassandra M Herring, Fuller W Bazer, Gregory A Johnson, Heewon Seo, Shengdi Hu, Mohammed Elmetwally, Wenliang He, Daniel B Long, Guoyao Wu.

BACKGROUND: Most embryonic loss in pigs occurs before d 30 of gestation. Dietary supplementation with L-arginine (Arg) during early gestation can enhance the survival and development of conceptuses (embryo/fetus and its extra-embryonic membranes) in gilts. However, the underlying mechanisms remain largely unknown.
METHODS: Between d 14 and 30 of gestation, each gilt was fed daily 2 kg of a corn- and soybean-meal based diet (12% crude protein) supplemented with either 0.4% Arg (as Arg-HCl) or an isonitrogenous amount of L-alanine (Control). There were 10 gilts per treatment group. On d 30 of gestation, gilts were fed either Arg-HCl or L-alanine 30 min before they were hysterectomized, followed by the collection of placentae, embryos, fetal membranes, and fetal fluids. Amniotic and allantoic fluids were analyzed for nitrite and nitrate [NOx; stable oxidation products of nitric oxide (NO)], polyamines, and amino acids. Placentae were analyzed for syntheses of NO and polyamines, water and amino acid transport, concentrations of amino acid-related metabolites, and the expression of angiogenic factors and aquaporins (AQPs).
RESULTS: Compared to the control group, Arg supplementation increased (P < 0.05) the number of viable fetuses by 1.9 per litter, the number and diameter of placental blood vessels (+ 25.9% and + 17.0% respectively), embryonic survival (+ 18.5%), total placental weight (+ 36.5%), the total weight of viable fetuses (+ 33.5%), fetal crown-to-rump length (+ 4.7%), and total allantoic and amniotic fluid volumes (+ 44.6% and + 75.5% respectively). Compared to control gilts, Arg supplementation increased (P < 0.05) placental activities of GTP cyclohydrolase-1 (+ 33.1%) and ornithine decarboxylase (+ 29.3%); placental syntheses of NO (+ 26.2%) and polyamines (+ 28.9%); placental concentrations of NOx (+ 22.5%), tetrahydrobiopterin (+ 21.1%), polyamines (+ 20.4%), cAMP (+ 27.7%), and cGMP (+ 24.7%); total amounts of NOx (+ 61.7% to + 96.8%), polyamines (+ 60.7% to + 88.7%), amino acids (+ 39% to + 118%), glucose (+ 60.5% to + 62.6%), and fructose (+ 41.4% to + 57.0%) in fetal fluids; and the placental transport of water (+ 33.9%), Arg (+ 78.4%), glutamine (+ 89.9%), and glycine (+ 89.6%). Furthermore, Arg supplementation increased (P < 0.05) placental mRNA levels for angiogenic factors [VEGFA120 (+ 117%), VEGFR1 (+ 445%), VEGFR2 (+ 373%), PGF (+ 197%), and GCH1 (+ 126%)] and AQPs [AQP1 (+ 280%), AQP3 (+ 137%), AQP5 (+ 172%), AQP8 (+ 165%), and AQP9 (+ 127%)].
CONCLUSION: Supplementing 0.4% Arg to a conventional diet for gilts between d 14 and d 30 of gestation enhanced placental NO and polyamine syntheses, angiogenesis, and water and amino acid transport to improve conceptus development and survival.

Keywords: Angiogenesis; Arginine; Fetus; Placenta; Reproduction

DOI: https://doi.org/10.1186/s40104-022-00794-0

J Comput Aided Mol Des. 2022 Dec 10.

A combined ligand and target-based virtual screening strategy to repurpose drugs as putrescine uptake inhibitors with trypanocidal activity.

Manuel A Llanos, Lucas N Alberca, María D Ruiz, María L Sbaraglini, Cristian Miranda, Agustina Pino-Martinez, Laura Fraccaroli, Carolina Carrillo, Catalina D Alba Soto, Luciana Gavernet, Alan Talevi.

Chagas disease, also known as American trypanosomiasis, is a neglected tropical disease caused by the protozoa Trypanosoma cruzi, affecting nearly 7 million people only in the Americas. Polyamines are essential compounds for parasite growth, survival, and differentiation. However, because trypanosomatids are auxotrophic for polyamines, they must be obtained from the host by specific transporters. In this investigation, an ensemble of QSAR classifiers able to identify polyamine analogs with trypanocidal activity was developed. Then, a multi-template homology model of the dimeric polyamine transporter of T. cruzi, TcPAT12, was created with Rosetta, and then refined by enhanced sampling molecular dynamics simulations. Using representative snapshots extracted from the trajectory, a docking model able to discriminate between active and inactive compounds was developed and validated. Both models were applied in a parallel virtual screening campaign to repurpose known drugs as anti-trypanosomal compounds inhibiting polyamine transport in T. cruzi. Montelukast, Quinestrol, Danazol, and Dutasteride were selected for in vitro testing, and all of them inhibited putrescine uptake in biochemical assays, confirming the predictive ability of the computational models. Furthermore, all the confirmed hits proved to inhibit epimastigote proliferation, and Quinestrol and Danazol were able to inhibit, in the low micromolar range, the viability of trypomastigotes and the intracellular growth of amastigotes.

Keywords: Chagas disease; Docking; Molecular dynamics; QSAR; TcPAT12; Virtual screening

DOI: https://doi.org/10.1007/s10822-022-00491-0