A study of branched-chain amino acid aminotransferase and isolation of mutations affecting the catabolism of branched-chain amino acids inSaccharomyces cerevisiae

Abstract Dietary phosphate intake is closely correlated with protein intake. However, the effects of the latter on phosphate-induced organ injuries remain uncertain. Herein, we investigated the effects of low (10.8%), moderate (23.0%), and high (35.2%) dietary casein and egg albumin administration on phosphate-induced organ injuries in rats. The moderate and high casein levels suppressed renal tubulointerstitial fibrosis and maintained mitochondrial integrity in the kidney. The serum creatinine levels were suppressed only in the high casein group. Phosphate-induced muscle weakness was also ameliorated by high dietary casein. The urinary and fecal phosphate levels in the early experiment stage showed that dietary casein did not affect phosphate absorption from the intestine. High dietary egg albumin showed similar kidney protective effects, while the egg albumin effects on muscle weakness were only marginally significant. As the plasma branched-chain amino acid levels were elevated in casein- and egg albumin-fed rats, we analyzed their effects. Dietary supplementation of 10% branched-chain amino acids suppressed phosphate-induced kidney injury and muscle weakness. Although dietary protein restriction is recommended in cases of chronic kidney disease, our findings indicate that the dietary casein, egg albumin, and branched-chain amino acid effects might be reconsidered in the era of a phosphate-enriched diet.

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Mechanism of De Novo Branched-Chain Amino Acid Synthesis as an Alternative Electron Sink in Hypoxic Aspergillus nidulans Cells

Applied and Environmental Microbiology ◽

10.1128/aem.02135-09 ◽

2010 ◽

Vol 76 (5) ◽

pp. 1507-1515 ◽

Cited By ~ 36

Author(s):

Motoyuki Shimizu ◽

Tatsuya Fujii ◽

Shunsuke Masuo ◽

Naoki Takaya

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Aspergillus Nidulans ◽

De Novo ◽

Acid Synthesis ◽

Branched Chain Amino Acids ◽

Amino Acid Synthesis ◽

Lactate Dehydrogenase Activity ◽

Branched Chain Amino Acid ◽

Branched Chain

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.

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Effect of Infused Branched-Chain Amino Acids on Muscle and Whole-Body Amino Acid Metabolism in Man

Clinical Science ◽

10.1042/cs0790457 ◽

1990 ◽

Vol 79 (5) ◽

pp. 457-466 ◽

Cited By ~ 105

Author(s):

Rita J. Louard ◽

Eugene J. Barrett ◽

Robert A. Gelfand

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Branched Chain Amino Acids ◽

Whole Body ◽

Acid Infusion ◽

Amino Acid Infusion ◽

Branched Chain Amino Acid ◽

Branched Chain

1. Using the forearm balance method, together with systemic infusions of l-[ring-2,6-3H]phenylalanine and l-[1-14C]leucine, we examined the effects of infused branched-chain amino acids on whole-body and skeletal muscle amino acid kinetics in 10 postabsorptive normal subjects; 10 control subjects received only saline. 2. Infusion of branched-chain amino acids caused a four-fold rise in arterial branched-chain amino acid levels and a two-fold rise in branched-chain keto acids; significant declines were observed in circulating levels of most other amino acids, including phenylalanine, which fell by 34%. Plasma insulin levels were unchanged from basal levels (8 ± 1 μ-units/ml). 3. Whole-body phenylalanine flux, an index of proteolysis, was significantly suppressed by branched-chain amino acid infusion (P < 0.002), and forearm phenylalanine production was also inhibited (P < 0.03). With branched-chain amino acid infusion total leucine flux rose, with marked increments in both oxidative and non-oxidative leucine disposal (P < 0.001). Proteolysis, as measured by endogenous leucine production, showed a modest 12% decrease, although this was not significant when compared with saline controls. The net forearm balance of leucine and other branched-chain amino acids changed from a basal net output to a marked net uptake (P < 0.001) during branched-chain amino acid infusion, with significant stimulation of local leucine disposal. Despite the rise in whole-body non-oxidative leucine disposal, and in forearm leucine uptake and disposal, forearm phenylalanine disposal, an index of muscle protein synthesis, was not stimulated by infusion of branched-chain amino acids. 4. The results suggest that in normal man branched-chain amino acid infusion suppresses skeletal muscle proteolysis independently of any rise of plasma insulin. Muscle branched-chain amino acid uptake rose dramatically in the absence of any apparent increase in muscle protein synthesis, as measured by phenylalanine disposal, or in branched-chain keto acid release. Thus, an increase in muscle branched-chain amino acid concentrations and/ or local branched-chain amino acid oxidation must account for the increased disposal of branched-chain amino acids.

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A Comparison of the Effects of Intravenous Infusion of Individual Branched-Chain Amino Acids on Blood Amino Acid Levels in Man

Clinical Science ◽

10.1042/cs0600095 ◽

1981 ◽

Vol 60 (1) ◽

pp. 95-100 ◽

Cited By ~ 51

Author(s):

S. Eriksson ◽

L. Hagenfeldt ◽

J. Wahren

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Intravenous Infusion ◽

Serum Insulin ◽

Aromatic Amino Acids ◽

Branched Chain Amino Acids ◽

Blood Concentrations ◽

Branched Chain Amino Acid ◽

Amino Acid Levels ◽

Branched Chain

1., Intravenous infusions of l-valine (600 μmol/min), l-isoleucine (150 μmol/min), l-leucine (300 μmol/min) and a mixture of the three branched-chain amino acids (70% l-leucine, 20% l-valine, 10% l-isoleucine; 270 μmol/min) were given to four groups of healthy volunteer subjects. Whole-blood concentrations of amino acids and glucose and serum insulin were measured before and during the infusions. 2. Valine and isoleucine infusions resulted in twelve- and six-fold increases in the respective amino acid. During valine infusion, tyrosine was the only amino acid for which a decrease in concentration was seen (25%, P < 0.05). With isoleucine administration, no significant changes were found. In contrast, leucine infusion (during which the leucine concentration rose about sixfold) was accompanied by significant decreases in tyrosine (35%), phenylalanine (35%), methionine (50%), valine (40%) and isoleucine (55%). The arterial glucose concentration fell slightly (5%) and the insulin concentration increased 20% during leucine infusion. 3. Infusion of the mixture of the three branched-chain amino acids resulted in marked decreases in tyrosine (50%), phenylalanine (50%) and methionine (35%). The decreased amino acid levels remained low for 2 h after the end of the infusion. 4. The present findings demonstrate that intravenous infusion of leucine (not infusion of valine or isoleucine) results in marked reductions in the concentrations of the aromatic amino acids and methionine. Infusion of a mixture of the three branched-chain amino acids gives results similar to those obtained with leucine infusion alone. Thus a mixed branched-chain amino acid solution with leucine as its main constituent seems to be the best alternative in the treatment of patients with hepatic cirrhosis and encephalopathy.

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BLOOD BRANCHED-CHAIN AMINO AND α-KETO ACID CONCENTRATIONS AND NET EXCHANGE ACROSS THE PORTAL-DRAINED VISCERA AND HINDLIMB OF FED AND FASTED RUMINANTS

Canadian Journal of Animal Science ◽

10.4141/cjas87-106 ◽

1987 ◽

Vol 67 (4) ◽

pp. 1011-1020 ◽

Cited By ~ 3

Author(s):

RICHARD J. EARLY ◽

JAMES R. THOMPSON ◽

ROBERT J. CHRISTOPHERSON ◽

GARY W. SEDGWICK

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Hind Limb ◽

Venous Blood ◽

Branched Chain Amino Acids ◽

Keto Acid ◽

Branched Chain Amino Acid ◽

Keto Acids ◽

Branched Chain ◽

Cattle And Sheep

In the first of two experiments, whole blood branched-chain amino acid (BCAA) and plasma branched-chain α-keto acid (BCKA) concentrations in jugular venous blood were determined in cattle and sheep before and during a 6-d fast. In cattle, concentrations of valine, isoleucine, α-ketoisovalerate (KIV) and α-ketomethylvalerate (KMV) remained unchanged whereas leucine and α-ketoisocaproate (KTC) increased (P < 0.05) during fasting. In sheep, only KIV and KMV remained unchanged whereas BCAA and KIC increased (P < 0.05) during fasting. In a second experiment on cattle chronically catheterized to measure BCAA and BCKA exchange across the portal-drained viscera (PDV) and hindlimb (HL), the PDV added and the HL removed BCAA from the blood of fed cattle. The opposite exchange occurred after a 6-d fast. Releases of BCKA from the PDV and HL in both fed and fasted states were small compared to BCAA exchanges. The data suggest that blood BCAA but not BCKA concentrations may respond differently to starvation in sheep versus cattle and that in cattle the PDV and HL do not release appreciable amounts of BCKA relative to the net movements of the BCAA. Key words: Portal-drained viscera, hind limb, branched-chain amino acids, branched-chain α-keto acids, fasting, ruminants

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Regulation of branched-chain amino acid metabolism and pharmacological effects of branched-chain amino acids

Hepatology Research ◽

10.1016/j.hepres.2004.09.001 ◽

2004 ◽

Vol 30 ◽

pp. 3-8 ◽

Cited By ~ 9

Author(s):

Y SHIMOMURA ◽

T MURAKAMI ◽

M NAGASAKI ◽

T HONDA ◽

H GOTO ◽

...

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Amino Acid Metabolism ◽

Acid Metabolism ◽

Branched Chain Amino Acids ◽

Pharmacological Effects ◽

Branched Chain Amino Acid ◽

Branched Chain

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Effects of amino acids on Thiobacillus acidophilus I. Growth studies with special reference to valine

Canadian Journal of Microbiology ◽

10.1139/m78-189 ◽

1978 ◽

Vol 24 (10) ◽

pp. 1158-1163

Author(s):

Gérald Proteau ◽

Marvin Silver

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Special Reference ◽

Branched Chain Amino Acids ◽

Heterotrophic Growth ◽

Branched Chain Amino Acid ◽

Crude Extracts ◽

Optimum Ph ◽

Thiobacillus Acidophilus ◽

Branched Chain

The heterotrophic growth of Thiobacillus acidophilus was inhibited by branched-chain amino acids; valine, isoleucine, and leucine. The inhibition by valine and leucine were partially reversed by isoleucine, and the inhibition by isoleucine was partially reversed by valine. Inhibitions by methionine or threonine were partially reversed when both amino acids were present in the growth medium. Inhibition by tyrosine was increased by phenylalanine or tryptophan. Cystine completely inhibited growth. Other amino acids tested produced little or no inhibition.Acetohydroxy acid synthetase (AHAS) activity was demonstrated in crude extracts of T. acidophilus. In crude extracts the optimum pH was 8.5 with a shift to 9.0 in the presence of valine. Valine was the only branched-chain amino acid which inhibited the AHAS activity. The presence of only one peak of AHAS activity upon centrifugation in linear glycerol density gradients demonstrated that the AHAS activity sediments as one component.

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Inactivation of the ilvB1 gene in Mycobacterium tuberculosis leads to branched-chain amino acid auxotrophy and attenuation of virulence in mice

Microbiology ◽

10.1099/mic.0.029884-0 ◽

2009 ◽

Vol 155 (9) ◽

pp. 2978-2987 ◽

Cited By ~ 30

Author(s):

Disha Awasthy ◽

Sheshagiri Gaonkar ◽

R. K. Shandil ◽

Reena Yadav ◽

Sowmya Bharath ◽

...

Keyword(s):

Amino Acids ◽

Mycobacterium Tuberculosis ◽

Amino Acid ◽

Mutant Strain ◽

Branched Chain Amino Acids ◽

Branched Chain Amino Acid ◽

Branched Chain ◽

Kinetics Of

Acetohydroxyacid synthase (AHAS) is the first enzyme in the branched-chain amino acid biosynthesis pathway in bacteria. Bioinformatics analysis revealed that the Mycobacterium tuberculosis genome contains four genes (ilvB1, ilvB2, ilvG and ilvX) coding for the large catalytic subunit of AHAS, whereas only one gene (ilvN or ilvH) coding for the smaller regulatory subunit of this enzyme was found. In order to understand the physiological role of AHAS in survival of the organism in vitro and in vivo, we inactivated the ilvB1 gene of M. tuberculosis. The mutant strain was found to be auxotrophic for all of the three branched-chain amino acids (isoleucine, leucine and valine), when grown with either C6 or C2 carbon sources, suggesting that the ilvB1 gene product is the major AHAS in M. tuberculosis. Depletion of these branched chain amino acids in the medium led to loss of viability of the ΔilvB1 strain in vitro, resulting in a 4-log reduction in colony-forming units after 10 days. Survival kinetics of the mutant strain cultured in macrophages maintained with sub-optimal concentrations of the branched-chain amino acids did not show any loss of viability, indicating either that the intracellular environment was rich in these amino acids or that the other AHAS catalytic subunits were functional under these conditions. Furthermore, the growth kinetics of the ΔilvB1 strain in mice indicated that although this mutant strain showed defective growth in vivo, it could persist in the infected mice for a long time, and therefore could be a potential vaccine candidate.

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Interference by branched-chain amino acids in the assay of alanine with alanine dehydrogenase

Biochemical Journal ◽

10.1042/bj1741079 ◽

1978 ◽

Vol 174 (3) ◽

pp. 1079-1082 ◽

Cited By ~ 5

Author(s):

P Lund ◽

G Baverel

Keyword(s):

Amino Acids ◽

Bacillus Subtilis ◽

Amino Acid ◽

Dehydrogenase Activity ◽

Branched Chain Amino Acids ◽

Acid Dehydrogenase ◽

Alanine Dehydrogenase ◽

Amino Acid Dehydrogenase ◽

Branched Chain Amino Acid ◽

Branched Chain

Commercial preparations of alanine dehydrogenase from Bacillus subtilis are contaminated to varying extents with activity towards branched-chain amino acids. The Km values for these amino acids are of the same order as for L-alanine (about 10(-3)M). The branched-chain amino acid dehydrogenase activity is lost on dialysis for 2–4h against water or 2mM-EDTA.

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Requirements for branched chain amino acids and their interactions in the nematode Caenorhabditis elegans

Nematology ◽

10.1163/156854100509411 ◽

2000 ◽

Vol 2 (5) ◽

pp. 501-506 ◽

Cited By ~ 4

Author(s):

Dalia Perelman ◽

Nancy Lu

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Caenorhabditis Elegans ◽

Branched Chain Amino Acids ◽

Nematode Caenorhabditis Elegans ◽

Optimal Range ◽

C Elegans ◽

Branched Chain Amino Acid ◽

High Concentrations ◽

Branched Chain

AbstractBranched chain amino acid (BCAA) requirements and their interactions were studied in the nematode Caenorhabditis elegans. Optimal, deficiency and toxic levels affecting nematode population growth were determined for each of the three BCAAs. The optimal range for leucine was 0.72-2.8; for isoleucine, 0.86-1.7; and for valine, 0.51-4.1 mg ml-1. Leucine at high concentrations was toxic. When isoleucine and valine were both added at high concentrations, they also exerted a marked toxic effect. The interactions of the branched chain amino acids found among vertebrate animals were not observed in C. elegans. Les besoins relatifs aux amino-acides en chaîne ramifiée et leurs interactions chez le nématode Caenorhabditis elegans - Les besoins relatifs aux amino-acides en chaîne ramifiée (BCAA) et leurs interactions ont été étudiés chez le nématode Caenorhabditis elegans. Les niveaux optimal, de déficience et toxique affectant la croissance de la population du nématode ont été déterminés pour chacune des BCAA. L'optimum est, pour la leucine de 0,72 à 2,8, pour l'isoleucine de 0,86 à 1,7 et pour la valine de 0,51 à 4,1 mg ml-1. A forte concentration la leucine est toxique. Si l'isoleucine et la valine sont ajoutées à forte concentration elles exercent également une action toxique prononcée. Les interactions entre BCAA observées chez les vertébrés ne l'ont pas été chez les C. elegans.

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