Microbial dynamics in seagrass restoration: Unveiling hidden indicators of ecological success.

Seagrass transplantation significantly alters sediment microbial communities, shaping their composition and metabolic functions. One year after Zostera marina transplantation, the microbial community structure and functions at the recipient site began shifting toward those of the donor site. Key microbial taxa associated with seagrass meadow sediment, such as Firmicutes (Hungateiclostridiaceae, Defluviitaleaceae) and Campylobacterota (Sulfurovum), increased in abundance, correlating with sediment organic matter content and carbon availability.

Natural Rubrolides and Their Synthetic Congeners as Inhibitors of the Photosynthetic Electron Transport Chain.

Rubrolides are a family of naturally occurring 5-benzylidenebutenolides, which generally contain brominated phenol groups, and nearly half of them also present a chlorine attached to the butenolide core. Seven natural rubrolides were previously synthesized. When these compounds were tested against the model plant , six were found to exert a slight inhibition on plant growth.

Guanidine production by plant homoarginine-6-hydroxylases.

Metabolism and biological functions of the nitrogen-rich compound guanidine have long been neglected. The discovery of four classes of guanidine-sensing riboswitches and two pathways for guanidine degradation in bacteria hint at widespread sources of unconjugated guanidine in nature. So far, only three enzymes from a narrow range of bacteria and fungi have been shown to produce guanidine, with the ethylene-forming enzyme (EFE) as the most prominent example.

A complex array of factors regulate the activity of Arabidopsis thaliana δ -pyrroline-5-carboxylate synthetase isoenzymes to ensure their specific role in plant cell metabolism.

The first and committed step in proline synthesis from glutamate is catalyzed by δ -pyrroline-5-carboxylate synthetase (P5CS). Two P5CS genes have been found in most angiosperms, one constitutively expressed to satisfy proline demand for protein synthesis, the other stress-induced. Despite the number of papers to investigate regulation at the transcriptional level, to date, the properties of the enzymes have been subjected to limited study.

Metabolic priming in G6PDH isoenzyme-replaced tobacco lines improves stress tolerance and seed yields via altering assimilate partitioning.

We investigated the basis for better performance of transgenic Nicotiana tabacum plants with G6PDH-isoenzyme replacement in the cytosol (Xanthi::cP2::cytRNAi, Scharte et al., 2009). After six generations of selfing, infiltration of Phytophthora nicotianae zoospores into source leaves confirmed that defence responses (ROS, callose) are accelerated, showing as fast cell death of the infected tissue.

The Levels of DAHP Synthase, the First Enzyme of the Shikimate Pathway, Are Related to Free Aromatic Amino Acids and Glutamine Content in Cell Cultures.

Aromatic amino acid homeostasis was investigated in cell suspension cultures of and was related to the activity of the first enzyme in aromatic biosynthesis, 3-deoxy-D--heptulosonate-7-phosphate (DAHP) synthase. An inverse relationship was found between the intracellular content of free phenylalanine, tyrosine and tryptophan and enzyme specific activity levels, suggesting the occurrence of end-product control mechanisms. Two DAHP synthase isogenes are present in wild tobacco that showed a different expression pattern during the culture growth cycle.

Sucrose Phosphate Synthase A2 Affects Carbon Partitioning and Drought Response.

Sucrose is essential for plants for several reasons: It is a source of energy, a signaling molecule, and a source of carbon skeletons. Sucrose phosphate synthase (SPS) catalyzes the conversion of uridine diphosphate glucose and fructose-6-phosphate to sucrose-6-phosphate, which is rapidly dephosphorylated by sucrose phosphatase. SPS is critical in the accumulation of sucrose because it catalyzes an irreversible reaction.

Functional Characterization of P5C Reductase, the Enzyme at the Converging Point of Proline and Arginine Metabolism.

The enzyme that, in catalyzes the last step in both proline synthesis and arginine catabolism, δ-pyrroline-5-carboxylate (P5C) reductase, was purified to near homogeneity and characterized thoroughly. Retention patterns upon gel permeation chromatography were consistent with a homodecameric composition of the holomer. High lability of the purified preparations and stabilization by reducing compounds suggested susceptibility to reactive-oxygen-species-mediated damage.

The Emerging Role of Proline in the Establishment and Functioning of Legume- Symbiosis.

High levels of some enzymes involved in proline synthesis and utilization were early found in soybean nodules, and rhizobial knockout mutants were shown to be defective in inducing nodulation and/or fixing nitrogen, leading to postulate that this amino acid may represent a main substrate for energy transfer from the plant to the symbiont. However, inconsistent results were reported in other species, and several studies suggested that proline metabolism may play an essential role in the legume- symbiosis only under stress. Different mechanisms have been hypothesized to explain the beneficial effects of proline on nodule formation and bacteroid differentiation, yet none of them has been conclusively proven.

Deciphering the structure of 5--pyruvyl-shikimate-3-phosphate synthase: An essential step toward the discovery of novel inhibitors to supersede glyphosate.

Glyphosate interferes with plant aromatic metabolism through the inhibition of 5--pyruvyl-shikimate-3-phosphate (EPSP) synthase [EPSPS, EC 2.5.1.

Enzymology and Regulation of δ-Pyrroline-5-Carboxylate Synthetase 2 From Rice.

Under several stress conditions, such as excess salt and drought, many plants accumulate proline inside the cell, which is believed to help counteracting the adverse effects of low water potential. This increase mainly relies upon transcriptional induction of δ-pyrroline-5-carboxylate synthetase (P5CS), the enzyme that catalyzes the first two steps in proline biosynthesis from glutamate. P5CS mediates both the phosphorylation of glutamate and the reduction of γ-glutamylphosphate to glutamate-5-semialdehyde, which spontaneously cyclizes to δ-pyrroline-5-carboxylate (P5C).

Peculiar substrate specificity of δ-pyrroline-5-carboxylate reductase in the obligately fermentative bacterium Zymomonas mobilis.

Background: The enzyme that catalyzes the last step in proline synthesis, δ-pyrroline-5-carboxylate reductase, showed in most cases a distinct preference in vitro for NADPH as the electron donor.

Methods And Results: A Zymomonas mobilis gene coding for a δ-pyrroline-5-carboxylate reductase was cloned and heterologously expressed, and the recombinant protein was purified and characterized. The enzyme showed higher affinity to, and higher catalytic rate with NADH, with a specific activity of about 600 nkat (mg protein).

Phenyl-substituted aminomethylene-bisphosphonates inhibit human P5C reductase and show antiproliferative activity against proline-hyperproducing tumour cells.

In certain cancers, such as breast, prostate and some lung and skin cancers, the gene for the enzyme catalysing the second and last step in proline synthesis, δ-pyrroline-5-carboxylate (P5C) reductase, has been found upregulated. This leads to a higher proline content that exacerbates the effects of the so-called proline-P5C cycle, with tumour cells effectively using this method to increase cell survival. If a method of reducing or inhibiting P5C reductase could be discovered, it would provide new means of treating cancer.

A comprehensive molecular approach to the detection of drug-type versus fiber-type hemp varieties.

The availability of molecular markers able to distinguish drug-type from fiber-type Cannabis sativa cultivars would allow fast and cheap analysis of any plant specimen, including seeds and leaves. Several approaches to this issue have been described, mainly using polymorphisms in the genes coding for tetrahydrocannabinol acid synthase or cannabidiolic acid synthase. Some studies reported sequencing of these genes from small groups of hemp varieties belonging to both chemotypes, showing the occurrence of specific DNA signatures.

Appropriate Activity Assays Are Crucial for the Specific Determination of Proline Dehydrogenase and Pyrroline-5-Carboxylate Reductase Activities.

Accumulation of proline is a widespread plant response to a broad range of environmental stress conditions including salt and osmotic stress. Proline accumulation is achieved mainly by upregulation of proline biosynthesis in the cytosol and by inhibition of proline degradation in mitochondria. Changes in gene expression or activity levels of the two enzymes catalyzing the first reactions in these two pathways, namely pyrroline-5-carboxylate (P5C) synthetase and proline dehydrogenase (ProDH), are often used to assess the stress response of plants.

A Specific and Sensitive Enzymatic Assay for the Quantitation of L-Proline.

Because proline accumulates rapidly in response to several stress conditions such as drought and excess salt, increased intracellular levels of free proline are considered a hallmark of adaptive reactions in plants, particularly in response to water stress. Proline quantitation is easily achievable by reaction with ninhydrin, since under acidic conditions peculiar red or yellow reaction products form with this unique cyclic amino acid. However, little attention has been paid to date to cross-reaction of ninhydrin with other amino acids at high levels, or with structurally related compounds that may also be present at significant concentrations in plant tissues, possibly leading to proline overestimation.

Impact of Drought on Soluble Sugars and Free Proline Content in Selected Mutants.

Water shortage is an increasing problem affecting crop yield. Accumulation of compatible osmolytes is a typical plant response to overcome water stress. Sucrose synthase 1 (SUS1), and glucan, water dikinase 2 (GWD2) and δ-pyrroline-5-carboxylate synthetase 1 (P5CS1) are members of small protein families whose role in the response of plants to mild osmotic stress has been studied in this work.

Synthesis of new tetronamides displaying inhibitory activity against bloom-forming cyanobacteria.

Background: The increasing frequency and intensity of cyanobacterial blooms pose a serious threat to aquatic ecosystems. These blooms produce potent toxins that can contaminate drinking water and endanger the life of wild and domestic animals as well as humans. Consequently, the development of effective methods for their control is a matter of high priority.

A fragment-like approach to PYCR1 inhibition.

Pyrroline-5-carboxylate reductase 1 (PYCR1) is the final enzyme involved in the biosynthesis of proline and has been found to be upregulated in various forms of cancer. Due to the role of proline in maintaining the redox balance of cells and preventing apoptosis, PYCR1 is emerging as an attractive oncology target. Previous PYCR1 knockout studies led to a reduction in tumor growth.

Carotenoid cleavage in chromoplasts of white and yellow-fleshed peach varieties.

Background: In peach fruit, carotenoid accumulation in the mesocarp causes the difference between yellow and white genotypes. The latter are generally characterized by a peculiar and more intense aroma, because of higher release of volatiles deriving from dioxygenase-catalysed breakdown of the tetraterpene skeleton. The rate of carotenoid oxidation was investigated in peach (Prunus persica L.

A differential tolerance to mild salt stress conditions among six Italian rice genotypes does not rely on Na exclusion from shoots.

Rice is very sensitive to salt stress at the seedling level, with consequent poor crop establishment. A natural variability in susceptibility to moderate saline environments was found in a group of six Italian temperate japonica rice cultivars, and the physiological determinants for salt tolerance were investigated. Cation (Na, K and Mg) levels were determined in shoots from individual rice plantlets grown in the absence or in the presence of inhibitory, yet sublethal salt levels, and at increasing time after salt treatments.

Preparation of Phosphonic Acid Analogues of Proline and Proline Analogues and Their Biological Evaluation as δ-Pyrroline-5-carboxylate Reductase Inhibitors.

Racemic 1-hydroxy-3-butenyl-, 3-chloro-1-hydroxypropyl-, and 3-bromo-1-hydroxypropylphosphonate and the corresponding ()-enantiomers obtained by lipase-catalyzed resolution of the respective racemic chloroacetates were subjected to functional group manipulations. These comprised ozonolysis, Mitsunobu reactions with hydrazoic acid and -hydroxyphthalimide, alkylation of hydrazine derivative, removal of phthaloyl group followed by intramolecular substitution, and global deprotection to deliver the racemates and ()-enantiomers (ee 92-99% by chiral high-performance liquid chromatography) of pyrrolidin-2-yl-, oxazolidin-3-yl-, oxazolidin-5-yl-, pyrazolidin-3-yl-, and 1,2-oxazinan-3-ylphosphonic acids. These phosphonic acids were evaluated as analogues of proline and proline analogues for the ability to inhibit γ-glutamyl kinase, δ-pyrroline-5-carboxylate synthetase, and δ-pyrroline-5-carboxylate reductase.

Tailoring Natural Abenquines To Inhibit the Photosynthetic Electron Transport through Interaction with the D1 Protein in Photosystem II.

Abenquines are natural N-acetylaminobenzoquinones bearing amino acid residues, which act as weak inhibitors of the photosynthetic electron transport chain. Aiming to exploit the abenquine scaffold as a model for the synthesis of new herbicides targeting photosynthesis, 14 new analogues were prepared by replacing the amino acid residue with benzylamines and the acetyl with different acyl groups. The synthesis was accomplished in three steps with a 68-95% overall yield from readily available 2,5-dimethoxyaniline, acyl chlorides, and benzyl amines.

Functional Characterization of Four Putative δ-Pyrroline-5-Carboxylate Reductases from .

In most living organisms, the amino acid proline is synthesized starting from both glutamate and ornithine. In prokaryotes, in the absence of an ornithine cyclodeaminase that has been identified to date only in a small number of soil and plant bacteria, these pathways share the last step, the reduction of δ-pyrroline-5-carboxylate (P5C) catalyzed by P5C reductase (EC 1.5.