Yeast Peptide Research Articles

Characterization and Identification of Yeast Peptides Released during Model Wine Fermentation and Lees Contact.

Aging wine on lees results in the release of different yeast components, including peptides, whose role in wine is unclear. In this study, peptides released in a synthetic must, fermented with an oenological yeast strain, and aged on lees for 180 days were quantified (RP-HPLC) and identified (LC-MS/MS) at different time points. A rapid increase in peptide concentration was observed in the first two months, with over 2600 sequences identified. During the following four months, the peptide concentration remained constant, while their variety decreased slightly, probably due to enzymatic hydrolysis to which longer and less charged sequences were more exposed. The majority of the most abundant peptides were present over the 6-month period. They mostly originated from proteins associated with glycolysis and with different stress-response mechanisms, and they showed different in silico bioactivities. These findings can contribute to understanding the role of yeast peptides in regulating the wine environment during aging.

Yeast peptides alleviate lipopolysaccharide-induced intestinal barrier damage in rabbits involving Toll-like receptor signaling pathway modulation and gut microbiota regulation.

Yeast peptides have garnered attention as valuable nutritional modifiers due to their potential health benefits. However, the precise mechanisms underlying their effects remain elusive. This study aims to explore the potential of yeast peptides, when added to diets, to mitigate lipopolysaccharide (LPS)-induced intestinal damage and microbiota alterations in rabbits. A total of 160 35-day-old Hyla line rabbits (0.96 ± 0.06 kg) were randomly assigned to 4 groups. These groups constituted a 2 × 2 factorial arrangement: basal diet (CON), 100 mg/kg yeast peptide diet (YP), LPS challenge + basal diet (LPS), LPS challenge +100 mg/kg yeast peptide diet (L-YP). The experiment spanned 35 days, encompassing a 7-day pre-feeding period and a 28-day formal trial. The results indicated that yeast peptides mitigated the intestinal barrier damage induced by LPS, as evidenced by a significant reduction in serum Diamine oxidase and D-lactic acid levels in rabbits in the L-YP group compared to the LPS group (p < 0.05). Furthermore, in the jejunum, the L-YP group exhibited a significantly higher villus height compared to the LPS group (p < 0.05). In comparison to the LPS group, the L-YP rabbits significantly upregulated the expression of Claudin-1, Occludin-1 and ZO-1 in the jejunum (p < 0.05). Compared with the CON group, the YP group significantly reduced the levels of rabbit jejunal inflammatory cytokines (TNF-α, IL-1β and IL-6) and decreased the relative mRNA expression of jejunal signaling pathway-associated inflammatory factors such as TLR4, MyD88, NF-κB and IL-1β (p < 0.05). Additionally, notable changes in the hindgut also included the concentration of short-chain fatty acids (SCFA) of the YP group was significantly higher than that of the CON group (p < 0.05). 16S RNA sequencing revealed a substantial impact of yeast peptides on the composition of the cecal microbiota. Correlation analyses indicated potential associations of specific gut microbiota with jejunal inflammatory factors, tight junction proteins, and SCFA. In conclusion, yeast peptides have shown promise in mitigating LPS-induced intestinal barrier damage in rabbits through their anti-inflammatory effects, modulation of the gut microbiota, and maintenance of intestinal tight junctions.

Effects of yeast peptides on the growth, antioxidant and anti-inflammatory capacities, immune function, and diarrhea status of suckling calves.

Yeast peptides, which are small-molecule active peptides extracted from yeast proteins, are known for their antibacterial, antioxidant, and anti-inflammatory properties. However, the effects of yeast peptide on suckling calves remain unclear. In this study, the effects of yeast peptide supplementation on the growth, diarrhea incidence, and immune function of calves during the suckling period were determined. Thirty newborn calves were randomly divided into two groups: the control group (CON) and the treatment group (AP), which received fresh pasteurized milk supplemented with yeast peptides (5 g/day). The experiment lasted for 49 days (7-56 days of age). The dry matter intake, body weight, diarrhea status, immune function, antioxidant capacity, and anti-inflammatory activity of the calves were analyzed. The AP group had higher dry matter intake, daily weight gain, and feed efficiency than the CON group (P < 0.05). Moreover, the duration and frequency of diarrhea were significantly lower in the AP group than in the CON group (P < 0.05). Furthermore, the immune, antioxidant, and anti-inflammatory capabilities of the AP group were significantly higher than those of the CON group (P < 0.05). These findings provide valuable insights for the improvement of early health management during calf rearing.

Anti-diabetic properties of brewer's spent yeast peptides. In vitro, in silico and ex vivo study after simulated gastrointestinal digestion.

Brewer's spent yeast (BSY) hydrolysates are a source of antidiabetic peptides. Nevertheless, the impact of in vitro gastrointestinal digestion of BSY derived peptides on diabetes has not been assessed. In this study, two BSY hydrolysates were obtained (H1 and H2) using β-glucanase and alkaline protease, with either 1 h or 2 h hydrolysis time for H1 and H2, respectively. These hydrolysates were then subjected to simulated gastrointestinal digestion (SGID), obtaining dialysates D1 and D2, respectively. BSY hydrolysates inhibited the activity of α-glucosidase and dipeptidyl peptidase IV (DPP-IV) enzymes. Moreover, although D2 was inactive against these enzymes, D1 IC50 value was lower than those found for the hydrolysates. Interestingly, after electrophoretic separation, D1 mannose-linked peptides showed the highest α-glucosidase inhibitory activity, while non-glycosylated peptides had the highest DPP-IV inhibitory activity. Kinetic analyses showed a non-competitive mechanism in both cases. After peptide identification, GILFVGSGVSGGEEGAR and IINEPTAAAIAYGLDK showed the highest in silico anti-diabetic activities among mannose-linked and non-glycosylated peptides, respectively (AntiDMPpred score: 0.70 and 0.77). Molecular docking also indicated that these peptides act as non-competitive inhibitors. Finally, an ex vivo model of mouse jejunum organoids was used to study the effect of D1 on the expression of intestinal epithelial genes related to diabetes. The reduction of the expression of genes that codify lactase, sucrase-isomaltase and glucose transporter 2 was observed, as well as an increase in the expression of Gip (glucose-dependent insulinotropic peptide) and Glp1 (glucagon-like peptide 1). This is the first report to evaluate the anti-diabetic effect of BSY peptides in mouse jejunum organoids.

Adapting an Isobaric Tag-Labeled Yeast Peptide Standard to Develop Targeted Proteomics Assays.

Targeted proteomics strategies present a streamlined hypothesis-driven approach to analyze specific sets of pathways or disease related proteins. goDig is a quantitative, targeted tandem mass tag (TMT)-based assay that can measure the relative abundance differences for hundreds of proteins directly from unfractionated mixtures. Specific protein groups or entire pathways of up to 200 proteins can be selected for quantitative profiling, while leveraging sample multiplexing permits the simultaneous analysis of up to 18 samples. Despite these benefits, implementing goDig is not without challenges, as it requires access to an instrument application programming interface (iAPI), an elution order and spectral library, a web-based method builder, and dedicated companion software. In addition, the absence of an example test assay may dissuade researchers from testing or implementing goDig. Here, we repurpose the TKO11 standard─which is commercially available but may also be assembled in-lab─and establish it as a de facto test assay for goDig. We build a proteome-wide goDig yeast library, quantify protein expression across several gene ontology (GO) categories, and compare these results to a fully fractionated yeast gold-standard data set. Essentially, we provide a guide detailing the goDig-based quantification of TKO11, which can also be used as a template for user-defined assays in other species.

Yeast Peptides Improve the Intestinal Barrier Function and Alleviate Weaning Stress by Changing the Intestinal Microflora Structure of Weaned Lambs.

Early weaning stress in lambs leads to decreased feed intake, damage to intestinal morphology, changes in the microbial flora structure, and subsequent complications. Yeast peptides are antimicrobial peptides with anti-inflammatory, antioxidant, and bacteriostasis effects. To study the effects of yeast peptides on relieving weaning stress in lambs, 54 lambs were randomly divided into three groups: ewe-reared (ER), yeast-peptide-treated (AP), and early-weaned (EW) lambs. The body weight and dry matter intake did not significantly differ among all groups. After weaning, the daily gain and feed conversion rate decreased significantly (p < 0.01), but AP showed an upward trend. In the EW group, immunoglobulin (Ig) levels changed significantly post-weaning (IgG decreased; IgA and IgM increased); the villi shortened, the crypt depth increased, and the villi height/crypt depth decreased (p < 0.001). The abundance and diversity of microflora among all groups were not significantly different. A column coordinate analysis showed significant differences in the intestinal microbial structure between the AP and EW groups. Lactobacillus, Aeriscardovia, Ruminosaceae_UCG-014, and Catenisphaera may play key roles in alleviating weaning stress in lambs. Our study provides new clues for alleviating weaning stress in lambs by describing the influence of yeast peptides on the intestinal microflora during weaning.

Probing the drivers of Staphylococcus aureus biofilm protein amyloidogenesis and disrupting biofilms with engineered protein disaggregases.

Phenol-soluble modulins (PSMs) are the primary proteinaceous component of Staphylococcus aureus biofilms. Residence in the protective environment of biofilms allows bacteria to rapidly evolve and acquire antimicrobial resistance, which can lead to persistent infections such as those caused by methicillin-resistant S. aureus (MRSA). In their soluble form, PSMs hinder the immune response of the host and can increase the virulence potential of MRSA. PSMs also self-assemble into insoluble functional amyloids that contribute to the structural scaffold of biofilms. The specific roles of PSM peptides in biofilms remain poorly understood. Here, we report the development of a genetically tractable yeast model system for studying the properties of PSMα peptides. Expression of PSMα peptides in yeast drives the formation of toxic insoluble aggregates that adopt vesicle-like structures. Using this system, we probed the molecular drivers of PSMα aggregation to delineate key similarities and differences among the PSMs and identified a crucial residue that drives PSM features. Biofilms are a major public health threat; thus, biofilm disruption is a key goal. To solubilize aggregates comprised of a diverse range of amyloid and amyloid-like species, we have developed engineered variants of Hsp104, a hexameric AAA+ protein disaggregase from yeast. Here, we demonstrate that potentiated Hsp104 variants counter the toxicity and aggregation of PSMα peptides. Further, we demonstrate that a potentiated Hsp104 variant can drive the disassembly of preformed S. aureus biofilms. We suggest that this new yeast model can be a powerful platform for screening for agents that disrupt PSM aggregation and that Hsp104 disaggregases could be a promising tool for the safe enzymatic disruption of biofilms. IMPORTANCE Biofilms are complex mixtures secreted by bacteria that form a material in which the bacteria can become embedded. This process transforms the properties of the bacteria, and they become more resistant to removal, which can give rise to multidrug-resistant strains, such as methicillin-resistant Staphylococcus aureus (MRSA). Here, we study phenol-soluble modulins (PSMs), which are amyloidogenic proteins secreted by S. aureus, that become incorporated into biofilms. Biofilms are challenging to study, so we have developed a new genetically tractable yeast model to study the PSMs. We used our system to learn about several key features of the PSMs. We also demonstrate that variants of an amyloid disaggregase, Hsp104, can disrupt the PSMs and, more importantly, dissolve preformed S. aureus biofilms. We propose that our system can be a powerful screening tool and that Hsp104 disaggregases may be a new avenue to explore for biofilm disruption agents.

Effect of yeast peptide dietary supplementation on nutrient digestibility, growth performance, and blood metabolites in geese

A study was conducted to evaluate the effect of yeast peptide supplementation on growth performance, nutrient digestibility, and blood metabolites in geese. One-day-old Sichuan white geese (n = 300, 95.16 ± 1.98 g) were randomly assigned to five dietary treatment groups containing either 0 (control), 100, 200, 300, or 400 mg/kg commercial yeast peptide product. Compared with the control, dietary supplemental yeast peptide at 200 mg/kg substantially improved feed conversion ratio, body slope length, half-eviscerated percentage, and the apparent digestibility of phosphorus. With the increase in dietary yeast peptide, breast width, carcass percentage, serum triglyceride and high-density lipoprotein increased linearly. The average daily gain, pelvis width, half-diving depth, low density lipoprotein, and digestibility of gross energy exhibited quadratic responses with the increase in dietary yeast peptide, with the 200 mg/kg or 300 mg/kg feeding level being the most effective. It can be concluded that dietary supplementation of yeast peptides improves growth performance and affects nutrient digestibility and blood metabolites, which were optimized at 200 mg/kg or 300 mg/kg of yeast peptide in the present study.

Peptide-rich extracts from spent yeast waste streams as a source of bioactive compounds for the nutraceutical market

Spent yeast is one of the main fermentation process by-products and several bioactive ingredients have been extracted from it, such as mannans and β-glucans. These extraction processes generate waste streams rich in protein, that can still be used to produce peptide-rich extracts. This work describes the use of a scalable and low-cost process to obtain yeast peptide extracts in a circular economy concept. Peptide fractions produced contained 48.3 to 86.4% of protein (w/w) and essential amino acids amounts higher than those defined by FAO and WHO references. Regarding their bioactive properties, extracts exhibited strong antihypertensive and antioxidant activities. Furthermore, an inhibition of 62.0–71.3% in HMG-CoA reductase was observed, a feature hereby described for the first time, thus stating the cholesterol-lowering capacity of yeast peptides. In conclusion, due to their combined nutritional and bioactive characteristics, the produced yeast peptide extracts are good candidates for dietary supplementation and functional foods.

Co-administering yeast polypeptide and the probiotic, Lacticaseibacillus casei Zhang, significantly improves exercise performance

Probiotics and peptides might can improve exercise performance. However, the effects of the combination of the two on athletic performance remains unclear. This study analyzed the effects of administering yeast polypeptide (YP) and/or Lacticaseibacillus casei Zhang (LCZ) on exercise performance in rats. The rats were randomized into four groups for 10-week dietary intervention, namely normal control (NC), polypeptide (YP), probiotics (LCZ, 4 × 109 CFU/d), and YP plus LCZ (YPZ). Then, a forced running-wheel protocol was implemented for three weeks. The multiple parameters, including exercise time, immune factors, gut microbiota, and serum metabolites were monitored. This study demonstrated that co-administering YP and LCZ significantly improved rats’ exercise time, and the beneficial effects were likely achieved through influencing the gut microbiota and serum metabolites. Our study presented a new method to improve exercise performance by supplementing with probiotics and yeast peptides, which may provide a new strategy for the development of functional foods.

Production of antioxidative protein hydrolysates from corn distillers solubles: Process optimization, antioxidant activity evaluation, and peptide analysis

Bioprospects of corn distillers solubles containing a unique thermally treated blend of corn and yeast from ethanol industries were evaluated. This includes alcalase hydrolysis optimization of protein concentrate, measurement of antioxidant activities, and peptide analysis. Response surface methodology (RSM) computed optimum values of enzyme: substrate ratio and incubation time, 5.2% (w/w) and 9.3 h. Besides, artificial neural network proved to be a good predictor of responses (R2 ~ 0.94–0.97) in agreement with RSM. The optimum RSM values maximized antioxidant yield, degree of hydrolysis, DPPH-, hydroxyl-, and superoxide-radical activities. The optimal PH and its three ultrafiltered fractions revealed higher scavenging activities against radicals of DPPH (76.15–85.66%), hydroxyl (81.26–91.91%), and superoxide (35.21–54.06%) at 5.0, 5.0, and 3.0 mg. mL−1, respectively. The foremost corn (QQPIIGGA, LPPYLSPA, SNIPLSPL, NPILQPY) and yeast (NIIPSPI) peptides were identified. The greater antioxidative characteristics might be due to more hydrophobic amino acids. The results are potent and pave the way forward for alternative valorized product streams in bioethanol industries.

Selenium-Rich Yeast Peptide Fraction Ameliorates Imiquimod-Induced Psoriasis-like Dermatitis in Mice by Inhibiting Inflammation via MAPK and NF-κB Signaling Pathways.

Psoriasis, a chronic and immune-mediated inflammatory disease, adversely affects patients’ lives. We previously prepared selenium-rich yeast peptide fraction (SeP) from selenium-rich yeast protein hydrolysate and found that SeP could effectively alleviate ultraviolet radiation-induced skin damage in mice and inhibited H2O2-induced cytotoxicity in cultured human epidermal keratinocyte (HaCaT) cells. This study aimed to investigate whether SeP had a protective effect on imiquimod (IMQ)-induced psoriasis-like dermatitis in mice and the underlying mechanisms. Results showed that SeP significantly ameliorated the severity of skin lesion in IMQ-induced psoriasis-like mouse model. Moreover, SeP treatment significantly attenuated the expression of key inflammatory cytokines, including interleukin (IL)-23, IL-17A, and IL-17F, in the dorsal skin of mice. Mechanistically, SeP application not only inhibited the activation of JNK and p38 MAPK, but also the translocation of NF-κB into the nucleus in the dorsal skin. Furthermore, SeP treatment inhibited the levels of inflammatory cytokines and the activation of MAPK and NF-κB signaling induced by lipopolysaccharide in HaCaT cells and macrophage cell line RAW264.7. Overall, our findings showed that SeP alleviated psoriasis-like skin inflammation by inhibiting MAPK and NF-κB signaling pathways, which suggested that SeP would have a potential therapeutic effect against psoriasis.

Identification of Two Novel Peptides That Inhibit α-Synuclein Toxicity and Aggregation.

Aggregation of α-synuclein (αSyn) into proteinaceous deposits is a pathological hallmark of a range of neurodegenerative diseases including Parkinson’s disease (PD). Numerous lines of evidence indicate that the accumulation of toxic oligomeric and prefibrillar αSyn species may underpin the cellular toxicity and spread of pathology between cells. Therefore, aggregation of αSyn is considered a priority target for drug development, as aggregation inhibitors are expected to reduce αSyn toxicity and serve as therapeutic agents. Here, we used the budding yeast S. cerevisiae as a platform for the identification of short peptides that inhibit αSyn aggregation and toxicity. A library consisting of approximately one million peptide variants was utilized in two high-throughput screening approaches for isolation of library representatives that reduce αSyn-associated toxicity and aggregation. Seven peptides were isolated that were able to suppress specifically αSyn toxicity and aggregation in living cells. Expression of the peptides in yeast reduced the accumulation of αSyn-induced reactive oxygen species and increased cell viability. Next, the peptides were chemically synthesized and probed for their ability to modulate αSyn aggregation in vitro. Two synthetic peptides, K84s and K102s, of 25 and 19 amino acids, respectively, significantly inhibited αSyn oligomerization and aggregation at sub-stoichiometric molar ratios. Importantly, K84s reduced αSyn aggregation in human cells. These peptides represent promising αSyn aggregation antagonists for the development of future therapeutic interventions.

Ultrafiltration performance of spent brewer's yeast protein hydrolysate: Impact of pH and membrane material on fouling

This work investigated membrane selectivity and fouling after the dead-end ultrafiltration of protein hydrolysate from spent brewer's yeast, a high protein brewing by-product. Ultrafiltration (UF) experiments were carried out with regenerated cellulose (RC) and polyethersulfone (PES) membranes of 30 kDa molecular weight cut-off at different pH values (5 and 8). Higher peptide retention (60% of total solids and 83% of peptides) was achieved using PES and a feed pH of 5. Ribonucleic acids were successfully separated from the peptide-rich fraction. The protein hydrolysate at pH 8 showed less susceptibility to the adsorption of proteins and smaller resistance to mass transfer. Similarities in the zeta potential of membranes and feed solution suggested that foulants aggregated in the surface of membranes by weak physical adsorption. Peptides were confirmed by FT-IR analysis as the main foulants. Hydrophilic membranes and feed at pH 8 increased UF performance of spent brewer's yeast hydrolysate. • Hydrophilicity and surface properties of membranes played a role on fouling. • Static tests and zeta potential results suggested a physical adsorption mechanism. • Separation of RNA from peptides is affected by yeast hydrolysate production method. • Peptides were separated from RNA using ultrafiltration membranes. • Yeast peptides hydrophobicity were monitored by surface tension measurement.

HYpro16: A Two-Proteome Mixture to Assess Interference in Isobaric Tag-Based Sample Multiplexing Experiments.

Isobaric tagging is a powerful strategy for global proteome profiling. A caveat of isobaric-tag-based quantification is "interference", which may be caused by coeluting peptides that are coisolated, cofragmented, and coanalyzed, thereby confounding quantitative accuracy. Here, we present a two-proteome standard that challenges the mass spectrometer to measure a range of protein abundance ratios in a background of potential interference. The HYpro16 standard consists of tandem mass tag (TMT) pro16-labeled human peptides at a 1:1 ratio across all channels into which is spiked TMTpro16-labeled yeast peptides in triplicate at 20:1, 10:1, 4:1, and 2:1 ratios. We showcase the HYpro16 standard by (1) altering the MS2 isolation window width and (2) examining different data acquisition methods (hrMS2, SPS-MS3, RTS-MS3). Our data illustrate that wider isolation widths moderately increase the TMT signal, the benefits of which are offset by decreased ratio accuracy. We also show that using real-time database searching (RTS)-MS3 resulted in the most accurate ratios. Additionally, the number of quantified yeast proteins using RTS-MS3 approaches that of hrMS2 when using a yeast-specific database for real-time searching. In short, this quality control standard allows for the assessment of multiple quantitative measurements within a single run, which can be compared across instruments to benchmark and track performance.

Antioxidant activity and inhibition of ultraviolet radiation-induced skin damage of Selenium-rich peptide fraction from selenium-rich yeast protein hydrolysate

The bioactive peptides and trace element selenium (Se) both have good antioxidant activity. However, whether combined Se and bioactive peptides have more excellent antioxidant activity remain unknown. The aim of this study is to prepare a Se-rich peptide fraction containing both Se and peptides from Se-rich yeast protein hydrolysate and investigated its antioxidant activity and effect on ultraviolet B (UVB) radiation-induced skin oxidative damage. The peptide fractions with different molecular weight (MW) and Se content were obtained by enzymatically hydrolyzing normal or Se-rich yeast proteins followed by a filtration process. In vitro free radical scavenging and lipid peroxidation inhibition assays showed that Se-rich peptides fraction with lower MW of <1 kDa (sSeP) had the highest antioxidant activity compared with Se-rich peptide fractions with higher MW of <3 kDa or normal peptide fractions. Oral administration of sSeP significantly decreased the level of malonaldehyde (MDA) in liver and serum, and increased the activity of glutathione peroxidase (GPx) in liver and serum in normal mice. When topically applied on the dorsal skin of mice, sSeP effectively alleviate UVB radiation-induced skin damage and oxidative stress by increasing GPx and catalase activities and glutathione content in skin or serum. Furthermore, sSeP showed a protective effect against H2O2-induced cytotoxicity in cultured human epidermal keratinocytes (HaCaT) cells probably by increasing aquaporin-3 expression and attenuating the phosphorylation of p38 MAPK. Overall, the results showed that Se-rich yeast peptide fraction containing Se and bioactive peptides could be a promising antioxidant nutrient used as food additive to enhance the body’s antioxidant ability or as cosmeceutical product to minimize the skin oxidative damage.

TomahaqCompanion: A Tool for the Creation and Analysis of Isobaric Label Based Multiplexed Targeted Assays.

Triggered by Offset, Multiplexed, Accurate mass, High resolution, and Absolute Quantitation (TOMAHAQ) is a recently introduced targeted proteomics method that combines peptide and sample multiplexing. TOMAHAQ assays enable sensitive and accurate multiplexed quantification by implementing an intricate data collection scheme that comprises multiple MSn scans, mass inclusion lists, and data-driven filters. Consequently, manual creation of TOMAHAQ methods can be time-consuming and error prone, while the resulting TOMAHAQ data may not be compatible with common mass spectrometry analysis pipelines. To address these concerns we introduce TomahaqCompanion, an open-source desktop application that enables rapid creation of TOMAHAQ methods and analysis of TOMAHAQ data. Starting from a list of peptide sequences, a user can perform each step of TOMAHAQ assay development including (1) generation of priming run target list, (2) analysis of priming run data, (3) generation of TOMAHAQ method file, and (4) analysis and export of quantitative TOMAHAQ data. We demonstrate the flexibility of TomahaqCompanion by creating a variety of methods testing TOMAHAQ parameters (e.g., number of SPS notches, run length, etc.). Lastly, we analyze an interference sample comprising heavy yeast peptides, a standard human peptide mixture, TMT11-plex, and super heavy TMT (shTMT) isobaric labels to demonstrate ∼10-200 attomol limit of quantification within a complex background using TOMAHAQ.

Antihypertensive effect of spent brewer yeast peptide

Abstract Numerous studies have investigated dietary approaches to prevent chronic lifestyle-related diseases, including hypertension. Spent brewer’s yeast is the second largest byproduct originated by the brewing industry and it deserves considerable attention because of its high nutritional value, ca. 40% of its dry mass is rich in protein which can be hydrolyzed into biologically active peptides. To upgrade this byproduct, the aim of this study was initially in vitro assessment of biological properties, e.g. ACE inhibition and antioxidant activity, and then, the in vivo effect in short-term oral antihypertensive effect of hydrolyzed yeast fractions on a well characterized model to study hypertension - Spontaneously Hypertensive Rats (SHR). Here, it was demonstrated that the fraction with molecular weight below 3 kDa containing tri and tetra- peptides with hydrophobic amino acid residues – SPQW, PWW and RYW, causes the most noticeable decrease in systolic, diastolic and mean blood pressure of SHR and shows highest antioxidant effect. These properties highlight the potential use of yeast extract as nutraceutical or functional food ingredient for the management and treatment of hypertension with antioxidant effect.

Uptake and intracellular fate of nona‐arginine peptide in yeast

AbstractCell‐penetrating peptides (CPPs) which are capable of crossing biological membranes are important tools for the delivery of cargo in modern day science and medicine. Mammalian cells are commonly used as model systems to study the uptake mechanism of several CPPs. In contrast, there are very few reports describing the mode of internalization of CPPs in fungal cells. Despite these studies, our understanding of the mechanism of translocation of CPPs in yeast is ambiguous. In this work, we evaluated the uptake of carboxyfluorescein‐labeled nona‐arginine (CF‐R9) CPP into the model yeast Saccharomyces cerevisiae. Translocation of R9 was concentration and time‐dependent and did not largely affect the viability of the cells. Endocytosis was the preferred mode of uptake when the cells were grown at 30 °C. A significant effect on the translocation of R9 was observed in cells treated with chemicals that inhibit energy‐dependent uptake and endocytosis. A substantial reduction in the uptake of the peptide was also observed in mutant cells lacking End3p, an essential protein for endocytosis. Interestingly, as proposed for other cell types, significant direct uptake was not observed in our experimental conditions. To our knowledge, this study for the first time reports the mechanism of translocation of R9 in yeast cells.

An Antimicrobial Peptide Induces FIG1-Dependent Cell Death During Cell Cycle Arrest in Yeast

Although most antibiotics act on cells that are actively dividing and non-dividing cells such as in microbe sporulation or cancer stem cells represent a new paradigm for the control of disease. In addition to their relevance to health, such antibiotics may promote our understanding of the relationship between the cell cycle and cell death. No antibiotic specifically acting on microbial cells arrested in their cell cycle has been identified until the present time. In this study we used an antimicrobial peptide derived from α-pheromone, IP-1, targeted against MATa Saccharomyces cerevisiae cells in order to assess its dependence on cell cycle arrest to kill cells. Analysis by flow cytometry and fluorescence microscopy of various null mutations of genes involved in biological processes activated by the pheromone pathway (the mitogen-activated protein kinase pathway, cell cycle arrest, cell proliferation, autophagy, calcium influx) showed that IP-1 requires arrest in G0/G1 in order to kill yeast cells. Isolating cells in different cell cycle phases by elutriation provided further evidence that entry into cell cycle arrest, and not into G1 phase, is necessary if our peptide is to kill yeast cells. We also describe a variant of IP-1 that does not activate the pheromone pathway and consequently does not kill yeast cells that express the pheromone’s receptor; the use of this variant peptide in combination with different cell cycle inhibitors that induce cell cycle arrest independently of the pheromone pathway confirmed that it is cell cycle arrest that is required for the cell death induced by this peptide in yeast. We show that the cell death induced by IP-1 differs from that induced by α-pheromone and depends on FIG1 in a way independent of the cell cycle arrest induced by the pheromone. Thus, IP-1 is the first molecule described that specifically kills microbial cells during cell cycle arrest, a subject of interest beyond the process of mating in yeast cells. The experimental system described in this study should be useful in the study of the mechanisms at play in the communication between cell cycle arrest and cell death on other organisms, hence promoting the development of new antibiotics.