scholarly journals A Yarrowia lipolytica Strain Engineered for Pyomelanin Production

2021 ◽  
Vol 9 (4) ◽  
pp. 838
Author(s):  
Macarena Larroude ◽  
Djamila Onésime ◽  
Olivier Rué ◽  
Jean-Marc Nicaud ◽  
Tristan Rossignol

The yeast Yarrowia lipolytica naturally produces pyomelanin. This pigment accumulates in the extracellular environment following the autoxidation and polymerization of homogentisic acid, a metabolite derived from aromatic amino acids. In this study, we used a chassis strain optimized to produce aromatic amino acids for the de novo overproduction of pyomelanin. The gene 4HPPD, which encodes an enzyme involved in homogentisic acid synthesis (4-hydroxyphenylpyruvic acid dioxygenase), was characterized and overexpressed in the chassis strain with up to three copies, leading to pyomelanin yields of 4.5 g/L. Homogentisic acid is derived from tyrosine. When engineered strains were grown in a phenylalanine-supplemented medium, pyomelanin production increased, revealing that the yeast could convert phenylalanine to tyrosine, or that the homogentisic acid pathway is strongly induced by phenylalanine.

2021 ◽  
Vol 8 ◽  
Author(s):  
Pegah Bagheri ◽  
Khang Hoang ◽  
Anthony A. Fung ◽  
Sahran Hussain ◽  
Lingyan Shi

Oxidative imbalance plays an essential role in the progression of many diseases that include cancer and neurodegenerative diseases. Aromatic amino acids (AAA) such as phenylalanine and tryptophan have the capability of escalating oxidative stress because of their involvement in the production of Reactive Oxygen Species (ROS). Here, we use D2O (heavy water) probed stimulated Raman scattering microscopy (DO-SRS) and two Photon Excitation Fluorescence (2PEF) microscopy as a multimodal imaging approach to visualize metabolic changes in HeLa cells under excess AAA such as phenylalanine or trytophan in culture media. The cellular spatial distribution of de novo lipogenesis, new protein synthesis, NADH, Flavin, unsaturated lipids, and saturated lipids were all imaged and quantified in this experiment. Our studies reveal ∼10% increase in de novo lipogenesis and the ratio of NADH to flavin, and ∼50% increase of the ratio of unsaturated lipids to saturated lipid in cells treated with excess phenylalanine or trytophan. In contrast, these cells exhibited a decrease in the protein synthesis rate by ∼10% under these AAA treatments. The cellular metabolic activities of these biomolecules are indicators of elevated oxidative stress and mitochondrial dysfunction. Furthermore, 3D reconstruction images of lipid droplets were acquired and quantified to observe their spatial distribution around cells’ nuceli under different AAA culture media. We observed a higher number of lipid droplets in excess AAA conditions. Our study showcases that DO-SRS imaging can be used to quantitatively study how excess AAA regulates metabolic activities of cells with subcellular resolution in situ.


2014 ◽  
Vol 14 (4) ◽  
pp. 935-946 ◽  
Author(s):  
Anna Czech ◽  
Malwina Merska ◽  
Katarzyna Ognik

Abstract The aim of this study was to determine immunological and biochemical blood indicators of turkey hens administered feed mixtures with 3 or 6% of Yarrowia lipolytica strain yeast as a dietary nutrient. The experiment was carried out on 240 turkey hens, aged from 1 to 16 weeks. The hens were randomly assigned to 3 experimental groups of 80 birds. Group I served as a control (K) and did not receive any experimental compounds. The turkey hens from experimental groups (YL3, YL6) were administered dried Yarrowia lipolytica yeast in two doses: 3% (YL3) and 6% (YL6) in feed mixtures. The study showed that the addition of Yarrowia lipolytica yeast in a dose of 3% but mainly in a dose of 6% stimulated the body’s immune defence mechanisms, which was evidenced by the increase in plasma lysozyme, % KF, IF, and reduction of monocyte ratio H/L in turkey hens. The advantage of using Yarrowia lipolytica in the nutrition of turkey hens was also a decrease in the content of blood indicators of lipid peroxidation such as CHOL, TG and LDL-cholesterol fraction, and an increase in the percentage of HDL-cholesterol fraction. The use of yeast component in the feeding of turkey hens affected the health status of birds and contributed to proper (not deviating from the reference values) biochemical indicators of metabolism.


2020 ◽  
Vol 12 (22) ◽  
pp. 9424 ◽  
Author(s):  
Magdalena Wróbel-Kwiatkowska ◽  
Waldemar Turski ◽  
Piotr Juszczyk ◽  
Agnieszka Kita ◽  
Waldemar Rymowicz

Y. lipolytica remains a nonpathogenic, unconventional yeast, which can be applied for the production of bioactive compounds. Our previous study confirmed the ability of yeast Yarrowia lipolytica to produce kynurenic acid (KYNA). Here, we investigated the effectiveness of KYNA production in cultures cultivated in medium containing honey of various origin, used as a source of carbon and energy. It was evidenced that the highest content of KYNA in culture broth (68 mg/L) and yeast biomass (542 mg/kg) was obtained when chestnut honey was used. The content of lipids and amino acids composition in yeast biomass producing KYNA was also determined. It was found that the composition of both amino acids and lipids in yeast biomass depended on the honey type used as a component of the medium. This finding revealed that supplementation of medium broth with honey may significantly affect the nutritional value of yeast biomass. The practical applicability of this finding requires further study.


2010 ◽  
Vol 76 (5) ◽  
pp. 1507-1515 ◽  
Author(s):  
Motoyuki Shimizu ◽  
Tatsuya Fujii ◽  
Shunsuke Masuo ◽  
Naoki Takaya

ABSTRACT Although branched-chain amino acids are synthesized as building blocks of proteins, we found that the fungus Aspergillus nidulans excretes them into the culture medium under hypoxia. The transcription of predicted genes for synthesizing branched-chain amino acids was upregulated by hypoxia. A knockout strain of the gene encoding the large subunit of acetohydroxy acid synthase (AHAS), which catalyzes the initial reaction of the synthesis, required branched-chain amino acids for growth and excreted very little of them. Pyruvate, a substrate for AHAS, increased the amount of hypoxic excretion in the wild-type strain. These results indicated that the fungus responds to hypoxia by synthesizing branched-chain amino acids via a de novo mechanism. We also found that the small subunit of AHAS regulated hypoxic branched-chain amino acid production as well as cellular AHAS activity. The AHAS knockout resulted in higher ratios of NADH/NAD+ and NADPH/NADP+ under hypoxia, indicating that the branched-chain amino acid synthesis contributed to NAD+ and NADP+ regeneration. The production of branched-chain amino acids and the hypoxic induction of involved genes were partly repressed in the presence of glucose, where cells produced ethanol and lactate and increased levels of lactate dehydrogenase activity. These indicated that hypoxic branched-chain amino acid synthesis is a unique alternative mechanism that functions in the absence of glucose-to-ethanol/lactate fermentation and oxygen respiration.


1997 ◽  
Vol 17 (5) ◽  
pp. 2511-2520 ◽  
Author(s):  
J J Smith ◽  
R K Szilard ◽  
M Marelli ◽  
R A Rachubinski

PEX genes encode peroxins, which are required for the biogenesis of peroxisomes. The Yarrowia lipolytica PEX17 gene encodes the peroxin Pex17p, which is 671 amino acids in length and has a predicted molecular mass of 75,588 Da. Pex17p is peripherally associated with the peroxisomal membrane. The carboxyl-terminal tripeptide, Gly-Thr-Leu, of Pex17p is not necessary for its targeting to peroxisomes. Synthesis of Pex17p is low in cells grown in glucose-containing medium and increases after the cells are shifted to oleic acid-containing medium. Cells of the pex17-1 mutant, the original mutant strain, and the pex17-KA mutant, a strain in which most of the PEX17 gene is deleted, fail to form normal peroxisomes but instead contain numerous large, multimembraned structures. The import of peroxisomal matrix proteins in these mutants is selectively impaired. This selective import is not a function of the nature of the peroxisomal targeting signal. We suggest a regulatory role for Pex17p in the import of a subset of matrix proteins into peroxisomes.


Cells ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1904 ◽  
Author(s):  
Nefertiti Muhammad ◽  
Hyun Min Lee ◽  
Jiyeon Kim

Amino acid metabolism promotes cancer cell proliferation and survival by supporting building block synthesis, producing reducing agents to mitigate oxidative stress, and generating immunosuppressive metabolites for immune evasion. Malignant cells rewire amino acid metabolism to maximize their access to nutrients. Amino acid transporter expression is upregulated to acquire amino acids from the extracellular environment. Under nutrient depleted conditions, macropinocytosis can be activated where proteins from the extracellular environment are engulfed and degraded into the constituent amino acids. The demand for non-essential amino acids (NEAAs) can be met through de novo synthesis pathways. Cancer cells can alter various signaling pathways to boost amino acid usage for the generation of nucleotides, reactive oxygen species (ROS) scavenging molecules, and oncometabolites. The importance of amino acid metabolism in cancer proliferation makes it a potential target for therapeutic intervention, including via small molecules and antibodies. In this review, we will delineate the targets related to amino acid metabolism and promising therapeutic approaches.


Weed Science ◽  
1981 ◽  
Vol 29 (3) ◽  
pp. 297-302 ◽  
Author(s):  
S. O. Duke ◽  
R. E. Hoagland

Several regimes of supplying exogenous aromatic amino acids to intact, 3-day-old, soybean [Glycine max(L.) Merr. ‘Hill’] seedlings by root uptake were tested to determine if growth retardation caused by root-fed, 0.5 mM glyphosate [N-(phosphonomethyl) glycine] could be reversed. Generally, root-fed levels of aromatic amino acids just below growth-retarding levels (e.g. 1 mM phenylalanine + 0.1 mM tyrosine) reversed root growth inhibition caused by glyphosate to a small (ca. 10%) but significant extent. Feeding aromatic amino acids for 1 to 3 days before glyphosate exposure did not enhance the reversal. Uptake and metabolism of root-fed, aromatic amino acids in control and glyphosate-treated plants were verified by increased levels of hydroxyphenolic compounds (end products of aromatic amino acid metabolism) and by uptake and incorporation of14C-labeled phenylalanine and tyrosine. On a fresh weight basis, glyphosate had no inhibitory effect on uptake or incorporation of these amino acids into protein or secondary phenolic compounds. After 3 days of exposure, glyphosate had no substantial effects on shikimate dehydrogenase activity in control or aromatic amino acid-fed seedlings. These data suggest that either root-fed aromatic amino acids are compartmentalized differently than the endogenous pools affected by glyphosate or that root-fed glyphosate exerts most of its effect on growth of soybean seedlings through means other than inhibition of aromatic amino acid synthesis.


Author(s):  
Gary W. Morrow

Like other amino acids, the aromatic amino acids phenylalanine, tyrosine, and tryptophan are vitally important for protein synthesis in all organisms. However, while animals can synthesize tyrosine via oxidation of phenylalanine, they can synthesize neither phenylalanine itself nor tryptophan and so these essential amino acids must be obtained in the diet, usually from plant material. Though many other investigators made significant contributions in this area over the years, it was Bernhard Davis in the early 1950s whose use of mutant stains of Escherichia coli led to a full understanding of the so-called shikimic acid pathway that is used by plants and also by some microorganisms for the biosynthesis of these essential amino acids. The pathway is almost completely devoted to their synthesis for protein production in bacteria, while in plants the pathway extends their use to the construction of a wide array of secondary metabolites, many of which are valuable medicinal agents. These secondary metabolites range from simple and familiar compounds such as vanillin (vanilla flavor and fragrance) and eugenol (oil of clove, a useful dental anesthetic) to more complex structures such as pinoresinol, a common plant biochemical, and podophyllotoxin, a powerful cancer chemotherapy agent. Earlier in Chapter 3, we encountered two important intermediates, erythrose-4-phosphate and phosphoenolpyruvate (PEP), each of which was derived from a different pathway utilized in carbohydrate metabolism. Erythrose-4-P was an intermediate in one of the steps of the pentose phosphate pathway while hydrolysis of PEP to pyruvic acid was the final step in glycolysis. These two simple intermediates provide the seven carbon atoms required for construction of shikimic acid itself. The two are linked to one another via a sequence of enzyme-mediated aldol-type reactions, the first being a bimolecular reaction and the second an intramolecular variant that ultimately leads to a cyclic precursor of shikimic acid known as 3-dehydroquinic acid as shown in Fig. 6.3. Subsequent dehydration of 3-dehydroquinic acid leads to 3-dehydroshikimic acid which then leads directly to shikimic acid via NADPH reduction.


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