Biology subjects

Gal, M.

Publications and source records attributed to Gal, M..

9 recordsLinked to original sources

bioRxiv2025

Psoriasin inhibits microbial growth in food by metal sequestering

Food spoilage is a significant economic and environmental concern, and it is estimated that [~]30% of fresh food is destroyed due to food spoilage between harvest to consumer. Current food preservatives are chemicals that are associated with various health risks and often have limited effectiveness under certain conditions like pH and temperature. Consequently, theres a growing need to develop effective, natural, and economical food preservatives. Herein, we studied the natural protein psoriasin as a potential food preservative. Psoriasin is naturally secreted in the oral cavity and has an effective and validated antimicrobial activity which makes it a potentially effective and safe protein-based food preservative. Indeed, our preliminary results show promising antimicrobial activity of the recombinant protein against food-related microbial organisms in vitro and in various food types. In addition, it is recombinantly expressed at high levels, which could set a cost-effective manufacturing process. These results set psoriasin as a safe and effective natural food preservative, addressing consumer demand for healthier food options and reducing food waste.

biochemistry↗

bioRxiv2025

Reversible and Causal Epigenetic Information Loss in Liver Aging and Disease

The loss of epigenetic information has been proposed as a driver of aging and diseases, but the reversibility and causality of this process remain underexplored. Here we analyze liver-unique methylation sites - genomic loci that show distinct methylation patterns in the liver compared to other tissues. Upon disease progression, these sites overwhelmingly regress toward the pan-tissue average. In addition, we demonstrate that this regression also occurs in a majority of these sites during normal aging. Using Mendelian randomization analysis, we identify significant enrichment of liver-unique methylation sites in causal aging-associated loci, particularly sites that are highly methylated in healthy liver. Remarkably, repeated fasting, a metabolic intervention known to improve liver function, partially restores the liver-unique methylation patterns at these sites. This restoration also occurs in isolated hepatocytes subjected to fasting-mimicking conditions, suggesting the effect is cell-autonomous rather than due to changes in tissue composition. The liver-unique methylation sites are enriched for binding sites of key metabolic transcription factors and show significant overlap with genetic variants associated with liver disease risk, suggesting a mechanistic link between epigenetic information loss and liver dysfunction. Our findings establish epigenetic information loss as both a marker and mediator of liver aging and disease, while demonstrating its potential reversibility through metabolic interventions. Graphical abstract: Reversible information loss at liver-unique methylation sitesLiver-unique sites, showing higher (UH) or lower (UL) methylation levels, regress to the pan-tissue average upon aging and disease. UH are enriched for methylation sites causal to the aging process, while UL are enriched for liver-specific enhancers and PPAR- binding sites. Upon repeated fasting, both UL and UH diverge away from the pan-tissue average, partially restoring the more youthful and disease-free epigenetic state. O_FIG O_LINKSMALLFIG WIDTH=174 HEIGHT=200 SRC="FIGDIR/small/639802v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@6d9ce9org.highwire.dtl.DTLVardef@58a2f6org.highwire.dtl.DTLVardef@132ff20org.highwire.dtl.DTLVardef@10b9acc_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2024

Enhancing Collagen Biosynthesis in Mammalian Cells Through Hypoxia-Mimetic Prolyl Hydroxylase Inhibition

Collagen, the most abundant protein in the extracellular matrix of mammalian cells, is extensively needed in various biotechnological and therapeutic applications, such as tissue engineering and regeneration, cosmetics, and cultivated meat. Despite the increasing demand for natural collagen from non-animal sources, it is mainly produced from animal connective tissues. Recent research has highlighted that under hypoxia, the activation of the hypoxia-inducible factor (HIF) leads to enhanced collagen type I biosynthesis. However, under normal oxygen conditions, HIF activity is downregulated by the HIF-prolyl hydroxylase (PHD) enzyme. We, therefore, hypothesized that inhibiting PHD could elevate HIF transcriptional activity and enhance collagen biosynthesis under normoxia. Our study demonstrates that inhibiting PHD using exogenous small molecules boosts HIF activity and upregulates the key enzymes, collagen prolyl 4-hydroxylases and lysyl hydroxylases, resulting in up to 29-fold increase in collagen type I in embryonic mouse fibroblast NIH/3T3 cells. These findings suggest that targeting PHD can effectively enhance collagen production in mammalian cells. Therefore, modulating key protein signaling pathways presents a promising strategy for enhancing the production of high-yield natural collagen.

cell biology↗

bioRxiv2024

Genetically encoded biosensor for fluorescence lifetime imaging of PTEN dynamics in the intact brain

The phosphatase and tensin homolog (PTEN) is a vital signaling protein which maintains an inhibitory brake that is critical for cellular metabolism, proliferation, and growth. The importance of PTEN signaling is evident from the broad spectrum of human pathologies associated with its loss of function. Moreover, loss or gain of PTEN function in animal models leads to aberrant cellular morphology, function, and metabolic regulation. However, despite the important role of PTEN signaling, there is currently no method to dynamically monitor its activity with cellular specificity within intact biological systems. Here, we describe the development of a novel PTEN biosensor, optimized for two-photon fluorescence lifetime imaging microscopy (2pFLIM). This biosensor is designed to measure PTEN activity within intact cells, tissues, and organisms. Our approach is based on monitoring FRET-dependent changes in PTEN conformation, which serves as a proxy for the activity state in living cells. We identify a point mutation that allow us to express this biosensor with minimal interference to endogenous PTEN signaling and cellular function. We demonstrate the utility of imaging PTEN signaling in cell lines, developing C. elegans, and in the living mouse brain. To complement this approach, we developed a red-shifted PTEN sensor variant that permits simultaneous imaging with GFP-based sensors. Finally, we use in vivo PTEN imaging in the mouse brain to identify cell-type specific dynamics of PTEN activity in excitatory and inhibitory cortical cells. In summary, our approach enables dynamic imaging of PTEN activity in vivo with unprecedented spatial and temporal resolution.

neuroscience↗

bioRxiv2024

Anti-fungal recombinant psoriasin effectively inhibits Candida albicans growth on denture base

Oral candidiasis leading to denture stomatitis is a fungal infection resulting from unregulated growth and adhesion mainly of Candida albicans onto acrylic denture base. Once the biofilm is formed, it is immune resistant and mainstay treatments involve toxic chemical antifungal agents or mechanical cleaning techniques, both offer limited efficacy. Consequently, there is an urgent need for more effective and safer therapeutic approaches. While biological modalities are expanding in general medicine, the exploration of protein-based therapeutics in dental medicine remains limited. This research evaluates the inhibitory effect of recombinantly expressed psoriasin on the growth of Candida albicans on polymethyl methacrylate denture bases. Psoriasin, also known as S100-A7, has shown promise in treating microbial skin infections, and its natural presence in saliva makes it a promising candidate for treating oral microbial infections. Our findings indicate that psoriasin exhibits a strong, dose-dependent inhibition of Candida albicans growth. Further, we incubated a polymethyl methacrylate denture base within the psoriasin solution. Notably, immersing the denture base in the solution completely eradicated fungal growth. Our research utilizes natural antifungal proteins within biomedical devices like denture bases, suggesting psoriasin as a safe alternative to chemical antifungals in dental medicine.

biochemistry↗

bioRxiv2024

Pesticide chemical leads inhibiting protein-protein interactions

Pesticides, especially herbicides, have revolutionized agriculture by providing energy-efficient solutions for pest control that replaces labor-intensive cultivation methods. However, the widespread evolution of pesticide resistance poses a significant challenge to current agriculture. Most pesticides function by binding to specific pockets on target enzymes, enabling a single mutation to confer resistance. An alternative approach is the disruption of protein-protein interactions (PPI), thus for resistance to occur, it requires complementary mutations on both interacting partners. Despite extensive efforts, no herbicides with new modes of action have been commercialized for decades. Thus, we focused on the discovery and design of small molecule inhibitors that target the interface of the PPI complex of O-acetylserine sulfhydrylase (OASS) and serine acetyltransferase (SAT), key plant enzymes involved in the biosynthesis of the essential amino acid cysteine. Using in silico filtering techniques on a virtual library of 30 million small molecules, we identified initial hits capable of binding OASS and interfering with its interaction with a peptide derived from SAT. Subsequently, we conducted chemical optimizations to evaluate biophysical enzyme disruption, followed by cellular and in-planta activity in plants. These new compounds described herein can serve as promising starting points for further optimization as herbicides acting on a new mode of action.

biochemistry↗

bioRxiv2024

Engineering of methionine-auxotroph Escherichia coli via parallel evolution of two enzymes from Corynebacterium glutamicum's direct-sulfurylation pathway enables its recovery in minimal medium

Methionine biosynthesis relies on the sequential catalysis of multiple enzymes. Escherichia coli, the main bacteria used in research and industry for protein production and engineering, utilizes the three-step trans-sulfurylation pathway catalyzed by L-homoserine O-succinyl transferase, cystathionine gamma synthase and cystathionine beta lyase to convert L-homoserine to L-homocysteine. However, most bacteria employ the two-step direct-sulfurylation pathway involving L-homoserine O-acetyltransferases and O-acetyl homoserine sulfhydrylase. We previously showed that a methionine-auxotroph E. coli strain (MG1655) with deletion of metA, encoding for L-homoserine O-succinyl transferase, and metB, encoding for cystathionine gamma synthase, could be complemented by introducing the genes metX, encoding for L-homoserine O-acetyltransferases and metY, encoding for O-acetyl homoserine sulfhydrylase, from various sources, thus altering the Escherichia coli methionine biosynthesis metabolic pathway to direct-sulfurylation. However, introducing metX and metY from Corynebacterium glutamicum failed to complement methionine auxotrophy. Herein, we generated a randomized genetic library based on the metX and metY of Corynebacterium glutamicum and transformed it into a methionine-auxotrophic E. coli strain lacking the metA and metB genes. Through multiple enrichment cycles, we successfully isolated active clones capable of growing in M9 minimal media without external methionine supplementation. The dominant metX mutations in the evolved methionine-autotrophs Escherichia coli were L315P and H46R. Interestingly, we found that a metY gene encoding only the N-terminus 106 out of 438 amino acids of the wild-type MetY enzyme is functional and supports the growth of the methionine auxotroph. Recloning the new genes into the original plasmid and transforming them to methionine auxotroph Escherichia coli validated their functionality. These results show that directed enzyme-evolution enables the fast engineering of new active variants within the Escherichia coli methionine direct-sulfurylation pathway, leading to efficient complementation.

biochemistry↗

bioRxiv2023

Nature-Inspired Peptide of MtDef4 C-terminus Tail Enables Protein Delivery in Mammalian Cells

Cell-penetrating peptides hold great promise as versatile tools for the intracellular delivery of therapeutic agents. Various peptides have originated from natural proteins with antimicrobial activity. In this study, we investigated the mammalian cell-penetrating properties of a 16-residue peptide derived from the C-terminus tail of the Medicago truncatula defensin protein, with the sequence GRCRHGFRRRCFCTTHC. We evaluated the ability of this peptide to penetrate multiple types of cells. Our results demonstrate that the peptide efficiently penetrates mammalian cells within minutes and at a sub-micromolar concentration. Moreover, upon N-terminal fusion to the fluorescent protein GFP, the peptide efficiently delivers the GFP into the cells. Despite its remarkable cellular penetration, the peptide has only a minor effect on cellular viability, making it a promising candidate for the development of a cell-penetrating peptide, with potential therapeutic applications.

cell biology↗

bioRxiv2023

Conversion of methionine biosynthesis in E. coli from trans- to direct-sulfurylation enhances extracellular methionine levels

Methionine is an essential amino acid in mammals and a critical metabolite in all organisms. As such, various applications, including food, feed, and pharmaceuticals, necessitate the addition of L-methionine. Although amino acids and other metabolites are commonly produced through bacterial fermentation, high-yield biosynthesis of L-methionine remains a significant challenge due to the strict cellular regulation of the biosynthesis pathway. As a result, methionine is produced primarily synthetically, resulting in a racemic mixture of D,L-methionine. This study aimed to enhance methionine bio-production yields in E. coli by replacing its highly regulated trans-sulfurylation pathway with the more common direct-sulfurylation pathway used by other bacteria. To this end, we generated an auxotroph E. coli strain (MG1655) by simultaneously deleting metA and metB genes and complementing them with metX and metY from different bacteria. Complementation of the genetically modified E. coli with metX/metY from Cyclobacterium marinum or Deinococcus geothermalis, together with the deletion of the global repressor metJ and overexpression of the transporter YjeH, resulted in a substantial increase of up to 126 and 160-fold methionine relative to the wild-type strain, respectively, and accumulation of up to 700 mg/L using minimal MOPS medium and 2 ml culture. Our findings provide a method to study methionine biosynthesis and a chassis for enhancing L-methionine production by fermentation. HighlightsO_LIReplacement of E. coli metA and metB with metX and metY recovered its growth C_LIO_LIThe engineered E. coli has a 160-fold increase in extracellular methionine levels C_LIO_LISelection of different metX and metY leads to varying growth rates and enhanced methionine levels C_LI

biochemistry↗