Interaction of phospholipid bilayers with polyamines of different length

Antibacterial activity of novel linear polyamines against Staphylococcus aureus

New therapeutic options are urgently required for the treatment of Staphylococcus aureus infections. Accordingly, we sought to exploit the vulnerability of S. aureus to naturally occurring polyamines. We have developed and tested the anti-staphylococcal activity of three novel linear polyamines based on spermine and norspermine. Using a panel of genetically distinct and clinically relevant multidrug resistant S. aureus isolates, including the polyamine resistant USA300 strain LAC, compound AHA-1394 showed a greater than 128-fold increase in inhibition against specific S. aureus strains compared to the most active natural polyamine. Furthermore, we show that AHA-1394 has superior biofilm prevention and biofilm dispersal properties compared to natural polyamines while maintaining minimal toxicity toward human HepG2 cells. We examined the potential of S. aureus to gain resistance to AHA-1394 following in vitro serial passage. Whole genome sequencing of two stable resistant mutants identified a gain of function mutation (S337L) in the phosphatidylglycerol lysyltransferase mprF gene. Inactivation of mutant mprF confirmed the importance of this allele to AHA-1394 resistance. Importantly, AHA-1394 resistant mutants showed a marked decrease in relative fitness and increased generation time. Intriguingly, mprF::S337L contributed to altered surface charge only in the USA300 background whereas increased cell wall thickness was observed in both USA300 and SH1000. Lastly, we show that AHA-1394 displays a particular proclivity for antibiotic potentiation, restoring sensitivity of MRSA and VRSA isolates to daptomycin, oxacillin and vancomycin. Together this study shows that polyamine derivatives are impressive drug candidates that warrant further investigation.

Effect of preharvest application of calcium chloride, putrescine, and salicylic acid on antioxidant system and biochemical changes of two Indian jujube genotypes

The effects of the preharvest application of calcium chloride (1 and 2%), salicylic acid (1 and 2 mM), and putrescine (1 and 2 mM) on the quality attributes and biochemical changes of two ber (Ziziphus mauritiana Lamk.) genotypes ("Sibi" and "Khormaee") were investigated at harvest and after 30 days of storage (5 ± 1°C and 85 ± 5% RH). The results showed that softening and weight loss in the treated fruit were significantly lower in comparison with the control. The antioxidant capacity of the fruit was higher in treated fruit than the control. Moreover, all the treatments significantly reduced the polyphenol oxidase (PPO) activity, increased the catalase (CAT) and peroxidase (POD) activities, and prevented the quick color change of ber fruit. The best overall visual quality (OVQ) was observed in the fruit treated with calcium chloride (1.5%) and putrescine (2 mM). Compared to the two genotypes, "Khormaee" showed a better appearance, relative to the "Sibi" genotypes. PRACTICAL APPLICATIONS: Ber (Ziziphus mauritiana Lamk.) fruit is a popular fruit which is cultivated widely in the tropical and subtropical countries of the world, due to its high nutritional value. It is rich in bioactive compounds and minerals. However, Indian jujube as a climacteric fruit is highly perishable and have a limited shelf life due to softening, browning, and shrinking. So that, the researchers still need more challenge to keep the quality of this fruit for consumers. In this study, the results showed that the preharvest application of calcium chloride (1.5%), putrescine (2 mM), and salicylic acid (2 mM) effectively kept the total quality of the Indian jujube fruit during storage by improving the firmness of the fruit, retarding the color change and browning, increasing the antioxidant enzymes such as; CAT and POD, and preserving the higher ascorbic acid. Therefore, these treatments can be useful to maintain the quality of Indian jujube during storage.

The biogenic amines putrescine and cadaverine show in vitro cytotoxicity at concentrations that can be found in foods

Putrescine and cadaverine are among the most common biogenic amines (BA) in foods, but it is advisable that their accumulation be avoided. Present knowledge about their toxicity is, however, limited; further research is needed if qualitative and quantitative risk assessments for foods are to be conducted. The present work describes a real-time analysis of the cytotoxicity of putrescine and cadaverine on intestinal cell cultures. Both BA were cytotoxic at concentrations found in BA-rich foods, although the cytotoxicity threshold for cadaverine was twice that of putrescine. Their mode of cytotoxic action was similar, with both BA causing cell necrosis; they did not induce apoptosis. The present results may help in establishing legal limits for both putrescine and cadaverine in food.

Molecular complementarity between simple, universal molecules and ions limited phenotype space in the precursors of cells

Background

Fundamental problems faced by the protocells and their modern descendants include how to go from one phenotypic state to another; escape from a basin of attraction in the space of phenotypes; reconcile conflicting growth and survival strategies (and thereby live on ‘the scales of equilibria’); and create a coherent, reproducible phenotype from a multitude of constituents.

Presentation of the hypothesis

The solutions to these problems are likely to be found with the organic and inorganic molecules and inorganic ions that constituted protocells, which we term SUMIs for Simple Universal Molecules and Ions. These SUMIs probably included polyphosphate (PolyP) as a source of energy and of phosphate; poly-(R)-3-hydroxybutyrate (PHB) as a source of carbon and as a transporter in association with PolyP; polyamines as a source of nitrogen; lipids as precursors of membranes; as well as peptides, nucleic acids, and calcium. Here, we explore the hypothesis that the direct interactions between PHB, PolyP, polyamines and lipids – modulated by calcium – played a central role in solving the fundamental problems faced by early and modern cells.

Testing the hypothesis

We review evidence that SUMIs (1) were abundant and available to protocells; (2) are widespread in modern cells; (3) interact with one another and other cellular constituents to create structures with new functions surprisingly similar to those of proteins and RNA; (4) are essential to creating coherent phenotypes in modern bacteria. SUMIs are therefore natural candidates for reducing the immensity of phenotype space and making the transition from a “primordial soup” to living cells.

Implications of the hypothesis

We discuss the relevance of the SUMIs and their interactions to the ideas of molecular complementarity, composomes (molecular aggregates with hereditary properties based on molecular complementarity), and a prebiotic ecology of co-evolving populations of composomes. In particular, we propose that SUMIs might limit the initial phenotype space of composomes in a coherent way. As examples, we propose that acidocalcisomes arose from interactions and self-selection among SUMIs and that the phosphorylation of proteins in modern cells had its origin in the covalent modification of proteins by PHB.

Reviewers

This article was reviewed by Doron Lancet and Kepa Ruiz-Mirazo.

Enhanced solubilization of membrane proteins by alkylamines and polyamines

Around 25% of proteins in living organisms are membrane proteins that perform many critical functions such as synthesis of biomolecules and signal transduction. Membrane proteins are extracted from the lipid bilayer and solubilized with a detergent for biochemical characterization; however, their solubilization is an empirical technique and sometimes insufficient quantities of proteins are solubilized in aqueous buffer to allow characterization. We found that addition of alkylamines and polyamines to solubilization buffer containing a detergent enhanced solubilization of membrane proteins from microsomes. The solubilization of polygalacturonic acid synthase localized at the plant Golgi membrane was enhanced by up to 9.9-fold upon addition of spermidine to the solubilization buffer. These additives also enhanced the solubilization of other plant membrane proteins localized in other organelles such as the endoplasmic reticulum and plasma membrane as well as that of an animal Golgi-localized membrane protein. Thus, addition of alkylamines and polyamines to solubilization buffer is a generally applicable method for effective solubilization of membrane proteins. The mechanism of the enhancement of solubilization is discussed.

Polyamine analogues: potent inducers of nucleosomal array oligomerization and inhibitors of yeast cell growth

Polyamines are naturally occurring intracellular polycations that are essential for viability and growth of eukaryotes. Dysregulation of polyamine metabolism is a hallmark of cancer and the carcinogenic process, and consequently development of polyamine analogues has emerged as a viable strategy for therapeutic intervention. Previously, we showed that the naturally occurring polyamines spermidine and spermine were quite effective at inducing the oligomerization of nucleosomal arrays in vitro, suggesting that polyamines may play a key role in regulating higher order chromatin structures in vivo. Here, we analyse the ability of a number of synthetic polyamine analogues to potentiate formation of higher order chromatin structures in vitro. We find that a class of long-chain polyamines called oligoamines are potent inducers of nucleosomal array oligomerization in vitro and that these same polyamine analogues rapidly block yeast cell growth.

Polyamines as a defense mechanism against lipoperoxidation in Trypanosoma cruzi

The polyamines, spermine and spermidine--organic polycations that are absolutely required for eukaryotic cell growth--are shown here to function in Trypanosoma cruzi epimastigotes, as protectors of membrane lipoperoxidation by reactive oxygen species generated either by H2O2/Fe2+ or nifurtimox. In vitro, spermine and spermidine inhibited lipoperoxidation in a dose dependent manner. Spermine was more efficient than spermidine in its inhibitory effect. Lipid peroxidation induced by H2O2 showed an IC50 of 0.55 mM for spermine and 0.9 mM for spermidine while an IC50 of 0.8 mM for spermine and 1.5 mM for spermidine were observed when lipoperoxidation was elicited by nifurtimox. Likewise in vivo, both exogenously added spermine and spermidine or endogenous increase of spermine levels induced by phorbol ester, protected against lipoperoxidation and decreased citotoxicity provoked by nifurtimox. Putrescine and cadaverine, also present in T. cruzi had no effect at all. None of the polyamines had any effect neither on the scavenging of superoxide anion nor on the regulation of antioxidant enzymes such as superoxide dismutase and peroxidases involved in H2O2 detoxification. Here we point out that spermine, by acting as a protector of membrane lipoperoxidation might contribute to survival of T. cruzi continuously exposed to oxidative stress.