Biosynthesis of Branched-Chain Amino Acids in Schizosaccharomyces pombe: Regulation of the Enzymes Involved in Isoleucine, Valine, and Leucine Synthesis

1974 ◽  
Vol 52 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Roderick A. McDonald ◽  
T. Satyanarayana ◽  
J. G. Kaplan
Keyword(s):  
Amino Acids ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Feedback Inhibition ◽  
Branched Chain Amino Acids ◽  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Threonine Deaminase ◽  
Branched Chain ◽  
Ph Range

The activities and regulation of the enzymes of the synthetic pathway of branched-chain amino acids were investigated in the fission yeast, Schizosaccharomyces pombe. Previous studies had shown the presence of threonine deaminase (TD) and acetohydroxy acid synthetase (AHAS). The remaining isoleucine–valine enzymes, isomeroreductase (IR), dehydrase, and transaminase B, have now been characterized in cell-free extracts, indicating the presence in this yeast of the complete pathway as demonstrated in other microorganisms. α-Isopropylmalate synthetase (IPMS), the first enzyme of the leucine pathway, has properties of a typical regulatory enzyme; it is most active in the pH range 7.5–8.5, but is most sensitive to feedback inhibition by L-leucine at pH 6.5–7.0. Unlike the situation in baker's yeast, only AHAS and IR appeared to be subject to multivalent repression. TD was relatively resistant to any change in level, and AHAS was repressible by valine included in the growth medium. IPMS was repressed when cells were grown in complex medium; leucine alone did not cause repression, and in contrast with baker's yeast, neither did leucine plus threonine or a combination of all three branched-chain amino acids.

Rapid Germination of Sulfonylurea-ResistantKochia scopariaL. Accessions is Associated with Elevated Seed Levels of Branched Chain Amino Acids

Weed Science ◽  
1993 ◽  
Vol 41 (1) ◽  
pp. 18-22 ◽  
Author(s):  
William E. Dyer ◽  
Peng W. Chee ◽  
Peter K. Fay
Keyword(s):  
Amino Acids ◽  
Thermal Gradient ◽  
Feedback Inhibition ◽  
Acetolactate Synthase ◽  
Branched Chain Amino Acids ◽  
Resistant Accession ◽  
Early Germination ◽  
Percent Germination ◽  
Soil Temperatures ◽  
Branched Chain

Field observations indicate that sulfonylurea-resistant kochia may germinate at lower soil temperatures and/or germinate more rapidly than susceptible kochia in the absence of herbicide. To investigate this possibility, seeds from three resistant and two susceptible kochia accessions were germinated at temperatures ranging from 4.6 to 13.2 C on thermal gradient plates. At 4.6 and 13.2 C, germination rates of all resistant accessions were higher than susceptible accessions, while germination rates of one resistant accession were higher than susceptible accessions at 7.2 and 10.5 C. Percent germination of all resistant accessions was significantly higher than susceptible accessions after 48 h at 4.6 C. At higher temperatures, percent germination of some resistant accessions was higher after 12 or 24 h, but germination of all accessions was similar at later times. HPLC analysis revealed that seeds from resistant accessions contained about 2-fold higher free levels of branched chain amino acids than seeds from susceptible accessions. The results indicate that mutations conferring resistance to sulfonylurea herbicides in these kochia accessions may concomitantly reduce or abolish acetolactate synthase sensitivity to normal feedback inhibition patterns, resulting in elevated levels of branched chain amino acids available for cell division and growth during early germination.

scholarly journals Metabolic engineering of Corynebacterium glutamicum for producing branched chain amino acids

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Shengzhu Yu ◽  
Bo Zheng ◽  
Zhenya Chen ◽  
Yi-Xin Huo
Keyword(s):  
Amino Acids ◽  
Metabolic Engineering ◽  
Corynebacterium Glutamicum ◽  
Animal Feed ◽  
Feedback Inhibition ◽  
Value Added ◽  
Branched Chain Amino Acids ◽  
High Yield ◽  
Acetohydroxy Acid Synthase ◽  
Branched Chain

Abstract Background Branched chain amino acids (BCAAs) are widely applied in the food, pharmaceutical, and animal feed industries. Traditional chemical synthetic and enzymatic BCAAs production in vitro has been hampered by expensive raw materials, harsh reaction conditions, and environmental pollution. Microbial metabolic engineering has attracted considerable attention as an alternative method for BCAAs biosynthesis because it is environmentally friendly and delivers high yield. Main text Corynebacterium glutamicum (C. glutamicum) possesses clear genetic background and mature gene manipulation toolbox, and has been utilized as industrial host for producing BCAAs. Acetohydroxy acid synthase (AHAS) is a crucial enzyme in the BCAAs biosynthetic pathway of C. glutamicum, but feedback inhibition is a disadvantage. We therefore reviewed AHAS modifications that relieve feedback inhibition and then investigated the importance of AHAS modifications in regulating production ratios of three BCAAs. We have comprehensively summarized and discussed metabolic engineering strategies to promote BCAAs synthesis in C. glutamicum and offer solutions to the barriers associated with BCAAs biosynthesis. We also considered the future applications of strains that could produce abundant amounts of BCAAs. Conclusions Branched chain amino acids have been synthesized by engineering the metabolism of C. glutamicum. Future investigations should focus on the feedback inhibition and/or transcription attenuation mechanisms of crucial enzymes. Enzymes with substrate specificity should be developed and applied to the production of individual BCAAs. The strategies used to construct strains producing BCAAs provide guidance for the biosynthesis of other high value-added compounds.

scholarly journals De Novo Biosynthesis of Vanillin in Fission Yeast (Schizosaccharomyces pombe) and Baker's Yeast (Saccharomyces cerevisiae)

2009 ◽  
Vol 75 (9) ◽  
pp. 2765-2774 ◽  
Author(s):  
Esben H. Hansen ◽  
Birger Lindberg Møller ◽  
Gertrud R. Kock ◽  
Camilla M. Bünner ◽  
Charlotte Kristensen ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
De Novo ◽  
Global Market ◽  
Baker’S Yeast ◽  
Yeast Cells ◽  
Vanillyl Alcohol ◽  
Baker's Yeast ◽  
Yeast Saccharomyces Cerevisiae

ABSTRACT Vanillin is one of the world's most important flavor compounds, with a global market of 180 million dollars. Natural vanillin is derived from the cured seed pods of the vanilla orchid (Vanilla planifolia), but most of the world's vanillin is synthesized from petrochemicals or wood pulp lignins. We have established a true de novo biosynthetic pathway for vanillin production from glucose in Schizosaccharomyces pombe, also known as fission yeast or African beer yeast, as well as in baker's yeast, Saccharomyces cerevisiae. Productivities were 65 and 45 mg/liter, after introduction of three and four heterologous genes, respectively. The engineered pathways involve incorporation of 3-dehydroshikimate dehydratase from the dung mold Podospora pauciseta, an aromatic carboxylic acid reductase (ACAR) from a bacterium of the Nocardia genus, and an O-methyltransferase from Homo sapiens. In S. cerevisiae, the ACAR enzyme required activation by phosphopantetheinylation, and this was achieved by coexpression of a Corynebacterium glutamicum phosphopantetheinyl transferase. Prevention of reduction of vanillin to vanillyl alcohol was achieved by knockout of the host alcohol dehydrogenase ADH6. In S. pombe, the biosynthesis was further improved by introduction of an Arabidopsis thaliana family 1 UDP-glycosyltransferase, converting vanillin into vanillin β-d-glucoside, which is not toxic to the yeast cells and thus may be accumulated in larger amounts. These de novo pathways represent the first examples of one-cell microbial generation of these valuable compounds from glucose. S. pombe yeast has not previously been metabolically engineered to produce any valuable, industrially scalable, white biotech commodity.

Heterologous Expression and Functional Characterization of Catalytic Subunit of Rice Acetohydroxyacid Synthase

2019 ◽  
Vol 26 (3) ◽  
pp. 176-183
Author(s):  
Ghazaleh Arabzadeh ◽  
Azar Shahpiri
Keyword(s):  
Amino Acids ◽  
Specific Activity ◽  
Feedback Inhibition ◽  
Functional Characterization ◽  
Branched Chain Amino Acids ◽  
Biochemical Properties ◽  
Catalytic Subunit ◽  
Acetohydroxyacid Synthase ◽  
Branched Chain

Background: Acetohydroxyacid Synthase (AHAS) is the first enzyme in the biosynthesis pathway of the branched chain amino acids. AHAS is the common target site of five herbicide chemical groups: sulfonylurea, imidazolinone, triazolopyrimidine, pyrimidinyl-thiobenzoates, and sulfonyl-aminocarbonyl-triazolinone. </P><P> Objective: The purification of protein enabled us to study the physical and biochemical properties of the enzyme. In addition in vitro activity of this enzyme was tested in the presence of four different sulfonylureaherbicides and the feedback regulation of enzyme was analyzed in the presence of branched amino acids. Methods: The gene encoding catalytic subunit of rice AHAS (cOsAHAS) without part of the chloroplast transit sequence was cloned into the bacterial expression vector pET41a and heterologously expressed in Escherichia coli as carboxy-terminal extensions of glutathione-S-transferase (GST).The soluble protein was purified using affinity chromatography. The measurement of GSTOsAHAS activity was performed under optimized conditions at present of branched-chain amino acids and sulfonylurea herbicides independently. Results: The optimum pH and temperature for GST-cOsAHAS activity was 8.0 and 37 °C, respectively. The specific activity and Km value of this enzyme toward pyruvate were 0.08 U/mg and 30 mM, respectively.GST-cOsAHAS was inhibited by herbicides tribenuron, sulfosulfuron, nicosulfuron and bensulfuron while the enzyme was insensitivieto end products. Conclusion: These results suggest that the recombinant form of GST-cOsAHAS is functionally active and carries the binding site for sulfynylurea herbicides. Furthermore, GST-cOsAHAS was insensitive to feedback inhibition by endproducts which indicates the existence of a regulator subunit in rice AHAS as previously has been described in other plant AHASs.

The Weight Loss Effects of Branched Chain Amino Acids and Vitamin B6: A Randomized Controlled Trial on Obese and Overweight Women

2018 ◽  
Vol 88 (1-2) ◽  
pp. 80-89 ◽  
Author(s):  
Zahra Shakibay Novin ◽  
Saeed Ghavamzadeh ◽  
Alireza Mehdizadeh
Keyword(s):  
Amino Acids ◽  
Weight Loss ◽  
Body Composition ◽  
Vitamin B6 ◽  
Controlled Trial ◽  
Density Lipoprotein ◽  
Branched Chain Amino Acids ◽  
Model Assessment ◽  
Waist To Hip Ratio ◽  
Branched Chain

Abstract. Branched chain amino acids (BCAA), with vitamin B6 have been reported to improve fat metabolism and muscle synthesis. We hypothesized that supplementation with BCAA and vitamin B6 would result in more weight loss and improve body composition and blood markers related to cardiovascular diseases. Our aim was to determine whether the mentioned supplementation would affect weight loss, body composition, and cardiovascular risk factors during weight loss intervention. To this end, we performed a placebo-controlled randomized clinical trial in 42 overweight and obese women (BMI = 25–34.9 kg/m2). Taking a four-week moderate deficit calorie diet (–500 kcal/day), participants were randomized to receive BCAA (6 g/day) with vitamin B6 (40 mg/day) or placebo. Body composition variables measured with the use of bioelectrical impedance analysis, homeostatic model assessment, and plasma insulin, Low density lipoprotein, High density lipoprotein, Total Cholesterol, Triglyceride, and fasting blood sugar were measured. The result indicated that, weight loss was not significantly affected by BCAA and vitamin B6 supplementation (–2.43 ± 1.02 kg) or placebo (–1.64 ± 1.48 kg). However, significant time × treatment interactions in waist to hip ratio (P = 0.005), left leg lean (P = 0.004) and right leg lean (P = 0.023) were observed. Overall, supplementation with BCAA and vitamin B6 could preserve legs lean and also attenuated waist to hip ratio.

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