Signalling pathway crosstalk stimulated by L-proline drives mouse embryonic stem cells to primitive-ectoderm-like cells.

The amino acid L-proline exhibits growth factor-like properties during development - from improving blastocyst development to driving neurogenesis in vitro. Addition of 400 µM L-proline to self-renewal medium drives naïve mouse embryonic stem cells (ESCs) to early primitive ectoderm-like (EPL) cells - a transcriptionally distinct primed or partially primed pluripotent state. EPL cells retain expression of pluripotency genes, upregulate primitive ectoderm markers, undergo a morphological change and have increased cell number. These changes are facilitated by a complex signalling network hinging on the Mapk, Fgfr, Pi3k and mTor pathways. Here, we use a factorial experimental design coupled with statistical modelling to understand which signalling pathways are involved in the transition between ESCs and EPL cells, and how they underpin changes in morphology, cell number, apoptosis, proliferation and gene expression. This approach reveals pathways which work antagonistically or synergistically. Most properties were affected by more than one inhibitor, and each inhibitor blocked specific aspects of the naïve-to-primed transition. These mechanisms underpin progression of stem cells across the in vitro pluripotency continuum and serve as a model for pre-, peri- and post-implantation embryogenesis.

Structural homology of mite profilins to plant profilins is not indicative of allergic cross-reactivity.

Structural and allergenic characterization of mite profilins has not been previously pursued to a similar extent as plant profilins. Here, we describe structures of profilins originating from Tyrophagus putrescentiae (registered allergen Tyr p 36.0101) and Dermatophagoides pteronyssinus (here termed Der p profilin), which are the first structures of profilins from Arachnida. Additionally, the thermal stabilities of mite and plant profilins are compared, suggesting that the high number of cysteine residues in mite profilins may play a role in their increased stability. We also examine the cross-reactivity of plant and mite profilins as well as investigate the relevance of these profilins in mite inhalant allergy. Despite their high structural similarity to other profilins, mite profilins have low sequence identity with plant and human profilins. Subsequently, these mite profilins most likely do not display cross-reactivity with plant profilins. At the same time the profilins have highly conserved poly(l-proline) and actin binding sites.

l-Proline and GelMA hydrogel complex：An efficient antifreeze system for cell cryopreservation.

Cryopreservation of biological samples is an important technology for expanding their applications in the biomedical field. However, the quality and functionality of samples after rewarming are limited by the toxicity of commonly used cryoprotectant agents (CPAs). Here, we developed a novel preservation system by combining the natural amino acid l-proline (L-Pro) with gelatin methacryloyl (GelMA) hydrogels. Compared with dimethyl sulfoxide (DMSO), L-Pro and GelMA demonstrated excellent biocompatibility when co-culturing with cells. Cryopreservation procedures were optimized using 3T3 as model cells. The results showed that rapid cooling was the most suitable cooling procedure for L-Pro and GelMA among the three cooling procedures. Co-culturing with cells for 3 h before cryopreservation, 6 % L-Pro +7 % GelMA had the highest survival rate, reaching up to 80 %. Differential Scanning Calorimetry (DSC) analysis showed that 6 % L-Pro + 7 % GelMA lowered the freezing point of the solution to -4.2 °C and increased the unfrozen water content to 20 %. To the best of our knowledge, this is the first report of cell cryopreservation using a combination of L-Pro and GelMA hydrogels, which provides a new strategy for improving cell cryopreservation.

Enhancing the production of L-proline in recombinant Escherichia coli BL21 by metabolic engineering.

L-proline is widely used in the fields of food, medicine and agriculture, and is also an important raw material for the synthesis of trans-4-hydroxy-L-proline. In this study, enhancing the production of L-proline by metabolic engineering was investigated. Three genes, proB, proA and proC, were introduced into Escherichia coli BL21 by molecular biology technology to increase the metabolic flow of L-proline from glucose. The genes putP and proP related to the proline transfer were knocked out by CRISPR/Cas9 gene editing technology to weaken the feedback inhibition of proB to increase the production of L-proline. The fermentation curves of the engineered strain at different glucose concentrations were determined, and a glucose concentration of 10 g/L was chosen to expand the batch culture to 1 L shake flask. Ultimately, through these efforts, the titer of L-proline reached 832.19 mg/L in intermittent glucose addition fermentation in a 1 L shake flask.

Recharacterization of the mammalian cytosolic type 2 (R)-ß-hydroxybutyrate dehydrogenase as 4-oxo-l-proline reductase (EC 1.1.1.104).

Early studies revealed that chicken embryos incubated with a rare analog of l-proline, 4-oxo-l-proline, showed increased levels of the metabolite 4-hydroxy-l-proline. In 1962, 4-oxo-l-proline reductase, an enzyme responsible for the reduction of 4-oxo-l-proline, was partially purified from rabbit kidneys and characterized biochemically. However, only recently was the molecular identity of this enzyme solved. Here, we report the purification from rat kidneys, identification, and biochemical characterization of 4-oxo-l-proline reductase. Following mass spectrometry analysis of the purified protein preparation, the previously annotated mammalian cytosolic type 2 (R)-ß-hydroxybutyrate dehydrogenase (BDH2) emerged as the only candidate for the reductase. We subsequently expressed rat and human BDH2 in Escherichia coli, then purified it, and showed that it catalyzed the reversible reduction of 4-oxo-l-proline to cis-4-hydroxy-l-proline via chromatographic and tandem mass spectrometry analysis. Specificity studies with an array of compounds carried out on both enzymes showed that 4-oxo-l-proline was the best substrate, and the human enzyme acted with 12,500-fold higher catalytic efficiency on 4-oxo-l-proline than on (R)-ß-hydroxybutyrate. In addition, human embryonic kidney 293T (HEK293T) cells efficiently metabolized 4-oxo-l-proline to cis-4-hydroxy-l-proline, whereas HEK293T BDH2 KO cells were incapable of producing cis-4-hydroxy-l-proline. Both WT and KO HEK293T cells also produced trans-4-hydroxy-l-proline in the presence of 4-oxo-l-proline, suggesting that the latter compound might interfere with the trans-4-hydroxy-l-proline breakdown in human cells. We conclude that BDH2 is a mammalian 4-oxo-l-proline reductase that converts 4-oxo-l-proline to cis-4-hydroxy-l-proline and not to trans-4-hydroxy-l-proline, as originally thought. We also hypothesize that this enzyme may be a potential source of cis-4-hydroxy-l-proline in mammalian tissues.

Structure-activity study of oncocin: On-resin guanidinylation and incorporation of homoarginine, 4-hydroxyproline or 4,4-difluoroproline residues.

Antimicrobial peptides (AMPs) often display guanidinium functionalities, and hence robust synthetic procedures are needed to facilitate access to analogues with unnatural homologues of arginine (Arg = R). Initially, a resin-bound Arg/Pro-rich fluoren-9-yl-methyloxycarbonyl-protected fragment (Fmoc-RPRPPR) of the AMP oncocin (i.e., VDKPPYLPRPRPPRRIYNR-NH2) was employed in a comparative on-resin assessment of commercial guanidinylation reagents head-to-head with the recently studied bis-Boc-protected triazole-based reagent, 1H-triazole-1-[N,N'-bis(tert-butoxycarbonyl)]-carboxamidine, which was synthesized by a chromatography-free procedure. This reagent was found to enable quantitative conversion in solid-phase peptide synthesis (SPPS) of peptides displaying homoarginine (Har) residues and/or an N-terminal guanidinium group. SPPS was used to obtain analogues of the 18-mer oncocin with single as well as multiple Arg → Har modifications. In addition, the effect of replacement of proline (Pro) residues in oncocin was explored by incorporating single or multiple trans-4-hydroxy-l-proline (Hyp) or 4,4-difluoro-l-proline (Dfp) residues, which both affected hydrophobicity. The resulting peptide library was tested against both Gram-negative and Gram-positive bacteria. Analysis of the minimal inhibitory concentrations (MICs) showed that analogues, displaying modifications at positions 4, 5 and 12 (originally Pro residues), had retained or slightly improved antimicrobial activity. Next, an oncocin analogue with two stabilizing l-Arg → d-Arg replacements in the C-terminal part was further modified by triple-replacement of Pro by either Dfp or Hyp in positions 4, 5, and 12. The resulting analogue displaying three Pro → Dfp modifications proved to possess the best activity profile: MICs of 1-2 µg/mL against E. coli and Klebsiella pneumoniae, less than 1% hemolysis at 800 µg/mL, and an IC50 above 1280 µg/mL in HepG2 cells. Thus, incorporation of bis-fluorinated Pro residues appears to constitute a novel tool in structure-activity studies aimed at optimization of Pro-rich AMPs.

Innovative electrochemical platform for the simultaneous determination of L-DOPA and L-tyrosine using layer-by-layer assembled L-proline-linked nanodiamonds on printed graphene.

Discovering alternative analytical techniques is crucial for practical applications; thus, this work aims to develop an innovative and simple electrochemical sensor for melanoma and the clinical diagnosis of related disorders by the simultaneous determination of 3,4-dihydroxy-L-phenylalanine (L-DOPA) and L-tyrosine (L-Tyr). The fabrication is based on the layer-by-layer electrodeposition of poly L-proline (poly(L-pro)) and nanodiamond (ND) onto a screen-printed graphene electrode (SPGE). The poly(L-pro)/ND/SPGEs were morphologically characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry, and Raman spectroscopy followed by electrochemical investigation using cyclic voltammetry, differential pulse voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. These modifier-based electrodes pave a feasible way to unlock the coexisting interfering substances from screen-printing ink composition and improve the sensitivity. Additionally, computational chemistry calculations were performed to fully comprehend the sensing behavior on both target analytes. Under optimal conditions, the developed sensor provided linear concentration ranges of 0.075-50 µM, with a detection limit of 0.021 µM for L-DOPA, and 2.5-120 µM with a detection limit of 0.74 µM for L-Tyr. To demonstrate the reliability of the poly(L-pro)/ND/SPGE in practical application, it was successfully applied to the determination of these analytes in human urine and blood serum samples, with satisfactory recovery ranges (81.73-110.62% for L-DOPA and 82.17-110.01% for L-Tyr) and relative standard deviations (0.69-9.90% for L-DOPA and 0.40-9.55% for L-Tyr). Due to its simplicity, long-term stability (> 87.8% of their initial currents after 35 days), and portability, the developed sensor is a promising alternative analytical method for on-site clinical monitoring.

Photocatalytic activity of visible-light-driven L-Proline-TiO2/BiOBr nanostructured materials for dyes degradation: The role of generated reactive species.

L-Proline (2%)-TiO2/BiOBr (30%) nanocomposite was synthesized to obtain high photocatalytic performance in the visible light region and infrared radiation(IR) for methylene blue (MB) and congo red (CR) removal from the contaminated wastewater. L-Proline (2%)-TiO2/BiOBr (30%) photocatalyst with strong absorption near IR wavelength and high charge separation ability was fabricated for the first time. X-ray diffraction (XRD), Fourier transform infrared (FTIR), field-emission scanning electron microscope (FESEM)/Energy Dispersive X-ray (EDX), UV-Vis diffuse reflectance spectrum (DRS), photoluminescence (PL) and Brunauer-Emmett-Teller (BET) characterization techniques show that the visible driven nanocomposite was successfully synthesized. According to the UV-DRS analysis, the estimated band gaps for the L-proline (2%)-TiO2 and L-Proline (2%)-TiO2/BiOBr (30%) nanostructures were respectively 2.3 eV and 2.1 eV.The nanoparticles exhibited enhanced photocatalytic activity (93-100%) and high mineralization efficiency (71-89% TOC removal) for both the dyes. The best photocatalytic activity was achieved by adding 2 wt% of L-Proline and 30 wt% of BiOBr into TiO2 sol. Response surface methodology (RSM) was employed to find significant parameters and their optimum values for maximum degradation, which show pH, dye concentration, irradiation time, and catalyst dosage for both the dyes are significant. The best photocatalytic degradation efficiency was achieved at the optimum conditions of pH = 7.7, catalyst dosage = 0.71 g/L, irradiation time = 142 and dye concentration = 11 mg/L for MB. Scavenger study showed that •OH radicals are responsible for the degradation process.

L-Proline Prevents Endoplasmic Reticulum Stress in Microglial Cells Exposed to L-azetidine-2-carboxylic Acid.

L-Azetidine-2-carboxylic acid (AZE) is a non-protein amino acid that shares structural similarities with its proteogenic L-proline amino acid counterpart. For this reason, AZE can be misincorporated in place of L-proline, contributing to AZE toxicity. In previous work, we have shown that AZE induces both polarization and apoptosis in BV2 microglial cells. However, it is still unknown if these detrimental effects involve endoplasmic reticulum (ER) stress and whether L-proline co-administration prevents AZE-induced damage to microglia. Here, we investigated the gene expression of ER stress markers in BV2 microglial cells treated with AZE alone (1000 µM), or co-treated with L-proline (50 µM), for 6 or 24 h. AZE reduced cell viability, nitric oxide (NO) secretion and caused a robust activation of the unfolded protein response (UPR) genes (ATF4, ATF6, ERN1, PERK, XBP1, DDIT3, GADD34). These results were confirmed by immunofluorescence in BV2 and primary microglial cultures. AZE also altered the expression of microglial M1 phenotypic markers (increased IL-6, decreased CD206 and TREM2 expression). These effects were almost completely prevented upon L-proline co-administration. Finally, triple/quadrupole mass spectrometry demonstrated a robust increase in AZE-bound proteins after AZE treatment, which was reduced by 84% upon L-proline co-supplementation. This study identified ER stress as a pathogenic mechanism for AZE-induced microglial activation and death, which is reversed by co-administration of L-proline.

Multicomponent Synthesis of 4-Aryl-4,9-dihydro-1H-pyrazolo[3,4-b]quinolines Using L-Proline as a Catalyst-Does It Really Proceed?

Looking for effective synthetic methods for 1H-pyrazolo[3,4-b]quinolines preparation, we came across a procedure where, in a three-component reaction catalysed by L-proline, 4-aryl-4,9-dihydro-1H-pyrazolo[3,4-b]quinolines are formed. These compounds can be easily oxidised to a fully aromatic system, which gives hope for a synthetic method that could replace, e.g., Friedländer condensation, often used for this purpose, even though severely limited by the availability of suitable substrates. However, after careful repetition of the procedures described in the publication, it turned out that the compounds described therein do not form at all. The actual compounds turned out to be 4,4-(phenyl-methylene)-bis-(3-methyl-1-phenylpyrazol-5-oles). Therefore, 4-Aryl-4,9-dihydro-1H-pyrazolo[3,4-b]quinolines were prepared by another method and used as standards to compare the products formed in the original procedure.

Acrylamide mitigation and 2,4-decadienal elimination in potato-crisps using L-proline accompanied by modified processing conditions.

Presence of toxic compounds such as acrylamide and 2,4-decadienal in fried products are dependent on frying temperature and time and the frying oil. Combination treatments such as aqueous pre-treatments of potato slices prior to frying; addition of L-proline to pre-treated samples; moisture reduction of samples pre-frying, replacement of refined soybean oil by deodorized-virgin-coconut oil (DVCO) as frying medium; and modification of frying time-temperature regime, were implemented to mitigate acrylamide and 2,4-decadienal in fried potato-crips, concomitantly enhancing their organoleptic quality. Based on similarity values of % acrylamide mitigation, experimental conditions were classified into four main clusters and the optimized conditions of the combination treatments obtained by central composite rotatable design were: blanching at 70 °C for 20 min; addition of 2% L-proline to pre-treated potato slices; and deep-frying in DVCO under modified frying conditions (140 °C, 5 min) successfully alleviated acrylamide (~ 99%) (confirmed by HR-MS and quantified by RP-HPLC) and 2,4-decadienal (quantified by RP-HPLC) in the fried potato-crisps, improving them sensorically. High Pearson's correlation co-efficient (r = 0.9955) was obtained between sensory scores and texture profile analyses data of the fried crisps. This mitigation strategy can be successfully extrapolated to industrial-scale frying for enhanced safety and sensory appeal of fried products. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-021-05328-6.

Modular reconstruction and optimization of the trans-4-hydroxy-L-proline synthesis pathway in Escherichia coli.

BACKGROUND: In recent years, there has been a growing demand for microbial production of trans-4-hydroxy-L-proline (t4Hyp), which is a value-added amino acid and has been widely used in the fields of medicine, food, and cosmetics. In this study, a multivariate modular metabolic engineering approach was used to remove the bottleneck in the synthesis pathway of t4Hyp. RESULTS: Escherichia coli t4Hyp synthesis was performed using two modules: a α-ketoglutarate (α-KG) synthesis module (K module) and L-proline synthesis with hydroxylation module (H module). First, α-KG attrition was reduced, and then, L-proline consumption was inhibited. Subsequently, to improve the contribution to proline synthesis with hydroxylation, optimization of gene overexpression, promotor, copy number, and the fusion system was performed. Finally, optimization of the H and K modules was performed in combination to balance metabolic flow. Using the final module H1K4 in a shaking flask culture, 8.80 g/L t4Hyp was produced, which was threefold higher than that produced by the W0 strain. CONCLUSIONS: These strategies demonstrate that a microbial cell factory can be systematically optimized by modular engineering for efficient production of t4Hyp.

Synthesis and in vitro/in vivo anticancer evaluation of pentacyclic triterpenoid derivatives linked with l-phenylalanine or l-proline.

Extensive research effort has been put in pentacyclic triterpenoids due to their numerous biological activities. However, their poor water solubility and low oral bioavailability limit their antitumor effects in vivo. To address these issues, 37 triterpenoid acid derivatives linked to l-phenylalanine or l-proline were designed and synthesized in this study. Structure-activity relationship (SAR) studies found two promising glycyrrhetinic acid (GA) derivatives 11 and 16. Compound 11 was obtained by C3-OH esterification and C30-COOH modification with l-phenylalanine while 16 was obtained by attaching C3-OH with l-phenylalanine. Compounds 11 and 16 exhibit up to 48- and 120-fold improvement respectively compared with the IC50 values of naturally occurring GA in the cellular assay. Fluorescence microscope and flow cytometric analysis suggested that both compounds 11 and 16 increased the content of ROS and Ca2+ in cancer cells, decreased mitochondrial membrane potential (JC-1), and activated the regulator caspase-3/8/9 to trigger cell apoptosis. RNA-seq analysis and western blot analysis indicated that compounds 11 and 16 may promote apoptosis by upregulating the functions of pro-apoptotic factors while inhibiting the proteasome activity.

The Role of SGLT2 Inhibitor Ipragliflozin on Cardiac Hypertrophy and microRNA Expression Profiles in a Non-diabetic Rat Model of Cardiomyopathy.

Evidence from clinical trials suggests that the cardioprotective effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors may arise through non-glycemic control-related mechanisms. Further, the cardiovascular advantages of SGLT2 inhibitors are likely present among non-diabetic patients with known cardiovascular diseases (CVDs). Here, we studied the impact of ipragliflozin, a selective SGLT2 inhibitor, on cardiac histopathology and microRNA (miRNA) expression profiles in a non-diabetic rat model of cardiomyopathy. Ipragliflozin was added to chow (0.01% (w/w)) and given to male DahlS.Z-Leprfa/Leprfa (DS/obese) rats for 6 weeks. Similarly aged male DahlS.Z-Lepr+/Lepr+ (DS/lean) rats were treated as controls. Measurements of systolic blood pressure (SBP) and heart rate (HR) were taken every other week. Following ipragliflozin treatment for 6 weeks, we conducted echocardiography, histopathological examination, and miRNA expression analysis (microarray). The impact of ipragliflozin on blood parameters was additionally examined. In DS/obese rats, ipragliflozin reduced SBP without affecting HR, reduced interventricular septal thickness in echocardiography and left ventricular (LV) organ weight, and improved hypertrophy of cardiomyocytes according to histopathological experiments. Further, ipragliflozin reduced plasma inflammatory cytokine levels in DS/obese rats. Additionally, ipragliflozin treatment altered the expression profile of miRNAs related to cardiac hypertrophy and heart failure in the LV compared to DS/obese control rats. Ipragliflozin prevented LV hypertrophy and altered related miRNA expression profiles in non-diabetic DS/obese rats. These findings suggest that miRNAs may play a partial role in regulating the structure of the heart and that SGLT2 inhibitors may exert cardio-protective effects by changing miRNA expression profiles in non-diabetic patients with CVDs.

Beneficial effect of L-Proline supplementation on the quality of human spermatozoa.

L-Proline is a natural anti-oxidative and osmoprotectant agent, playing a versatile role in cell metabolism and physiology. The present study aimed to explore the antioxidant effects of L-Proline on human sperm function during incubation. Thirty healthy, normozoospermic men (27-40 years) were enrolled. Sperm samples were incubated in an unsupplemented sperm medium (control group), or supplemented with L-Proline (1, 2 and 4 mmol/L) to evaluate its effect during 0, 1, 4 and 24 h of incubation. Sperm were assessed in terms of motility, viability, morphology, chromatin and DNA integrity. Moreover, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and total antioxidant capacity (TAC) were determined in the sperm medium. The results indicated that 2 mmol/L of L-Proline significantly improved the maintenance of sperm motility, viability, normal morphology, chromatin and DNA integrity, and TAC levels compared to the control group during 24 h of incubation (p < 0.05). However, 1 and 4 mmol/L of L-Proline could not significantly preserve sperm parameters, chromatin quality, and antioxidant status during different incubation times compared to the control group (p > 0.05). Collectively, the inclusion of L-Proline (2 mmol/L) in the human sperm medium maintains sperm parameters and chromatin quality probably by modulating the oxidative status.

L-proline as a novel additive to cryopreservation media improved post-thaw quality of human spermatozoon via reducing oxidative stress.

Sperm cryopreservation as a routine technique in assisted reproductive technique (ART) laboratories has detrimental effects on spermatozoa. Various methods have been introduced to improve it. The aim of this research was to evaluate the effects of L-proline supplementation in cryopreservation medium on normozoospermic semen samples. A total of 30 semen samples were collected from normozoospermic men. Cryopreservation media were supplemented with different concentrations of L-proline (0, 1, 2 and 4 mmol/L). The semen samples were cryopreserved. After thawing, sperm parameters and chromatin integrity (aniline blue (AB), toluidine blue (TB), sperm chromatin dispersion test (SCD) and chromomycin A3 (CMA3)), reactive oxygen species (ROS), and total antioxidant capacity (TAC) and malondialdehyde (MDA) levels were evaluated. A total of 4 mmol/L L-proline significantly improved progressive motility and viability (p < 0.05). MDA and ROS levels significantly diminished in samples were cryopreserved by 4 mmol/L L-proline supplemented cryopreservation media (p < 0.001). Also, it significantly increased TAC level. Also, chromatin damages (AB, TB and CMA3) significantly improved in samples were cryopreserved by 4 mmol/L L-proline supplemented cryopreservation media (p < 0.05). The results support that the usage of L-proline supplemented cryopreservation media to improve sperm quality after cryopreservation.

Simultaneous Electrochemical Sensing of Indole-3-Acetic Acid and Salicylic Acid on Poly(L-Proline) Nanoparticles-Carbon Dots-Multiwalled Carbon Nanotubes Composite-Modified Electrode.

Sensitive simultaneous electrochemical sensing of phytohormones indole-3-acetic acid and salicylic acid based on a novel poly(L-Proline) nanoparticles-carbon dots composite consisting of multiwalled carbon nanotubes was reported in this study. The poly(L-Proline) nanoparticles-carbon dots composite was facilely prepared by the hydrothermal method, and L-Proline was used as a monomer and carbon source for the preparation of poly(L-Proline) nanoparticles and carbon dots, respectively. Then, the poly(L-Proline) nanoparticles-carbon dots-multiwalled carbon nanotubes composite was prepared by ultrasonic mixing of poly(L-Proline) nanoparticles-carbon dots composite dispersion and multiwalled carbon nanotubes. Scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, ultraviolet visible spectroscopy, energy dispersive spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and linear sweep voltammetry were used to characterize the properties of the composite. poly(L-Proline) nanoparticles were found to significantly enhance the conductivity and sensing performance of the composite. Under optimal conditions, the composite-modified electrode exhibited a wide linear range from 0.05 to 25 µM for indole-3-acetic acid and from 0.2 to 60 µM for salicylic acid with detection limits of 0.007 µM and 0.1 µM (S/N = 3), respectively. In addition, the proposed sensor was also applied to simultaneously test indole-3-acetic acid and salicylic acid in real leaf samples with satisfactory recovery.

Profilin2a-phosphorylation as a regulatory mechanism for actin dynamics.

Profilin is a major regulator of actin dynamics in multiple specific processes localized in different cellular compartments. This specificity is not only meditated by its binding to actin but also its interaction with phospholipids such as phosphatidylinositol (4,5)-bisphosphate (PIP2 ) at the membrane and a plethora of proteins containing poly-L-proline (PLP) stretches. These interactions are fine-tuned by posttranslational modifications such as phosphorylation. Several phospho-sites have already been identified for profilin1, the ubiquitously expressed isoform. However, little is known about the phosphorylation of profilin2a. Profilin2a is a neuronal isoform important for synapse function. Here, we identified several putative profilin2a phospho-sites in silico and tested recombinant phospho-mimetics with regard to their actin-, PLP-, and PIP2 -binding properties. Moreover, we assessed their impact on actin dynamics employing a pyrene-actin polymerization assay. Results indicate that distinct phospho-sites modulate specific profilin2a functions. We could identify a molecular switch site at serine residue 71 which completely abrogated actin binding-as well as other sites important for fine-tuning of different functions, for example, tyrosine 29 for PLP binding. Our findings suggest that differential profilin2a phosphorylation is a sensitive mechanism for regulating its neuronal functions. Moreover, the dysregulation of profilin2a phosphorylation may contribute to neurodegeneration.

Proline dehydrogenase in cancer: apoptosis, autophagy, nutrient dependency and cancer therapy.

L-proline catabolism is emerging as a key pathway that is critical to cellular metabolism, growth, survival, and death. Proline dehydrogenase (PRODH) enzyme, which catalyzes the first step of proline catabolism, has diverse functional roles in regulating many pathophysiological processes, including apoptosis, autophagy, cell senescence, and cancer metastasis. Notably, accumulated evidence demonstrated that PRODH plays complex role in many types of cancers. In this review, we briefly introduce the function of PRODH, then its expression in different types of cancer. We next discuss the regulation of PRODH in cancer, the downstream pathways of PRODH and the therapies that are under investigation. Finally, we propose novel insights for future perspectives on the modulation of PRODH.

Metabolic engineering strategy for synthetizing trans-4-hydroxy-L-proline in microorganisms.

Trans-4-hydroxy-L-proline is an important amino acid that is widely used in medicinal and industrial applications, particularly as a valuable chiral building block for the organic synthesis of pharmaceuticals. Traditionally, trans-4-hydroxy-L-proline is produced by the acidic hydrolysis of collagen, but this process has serious drawbacks, such as low productivity, a complex process and heavy environmental pollution. Presently, trans-4-hydroxy-L-proline is mainly produced via fermentative production by microorganisms. Some recently published advances in metabolic engineering have been used to effectively construct microbial cell factories that have improved the trans-4-hydroxy-L-proline biosynthetic pathway. To probe the potential of microorganisms for trans-4-hydroxy-L-proline production, new strategies and tools must be proposed. In this review, we provide a comprehensive understanding of trans-4-hydroxy-L-proline, including its biosynthetic pathway, proline hydroxylases and production by metabolic engineering, with a focus on improving its production.