Methylmalonate-Semialdehyde Dehydrogenase (Acylating)
Brain Diseases, Metabolic, Inborn
Amino Acid Metabolism, Inborn Errors
An integrated study of threonine-pathway enzyme kinetics in Escherichia coli. (1/46)We have determined the kinetic parameters of the individual steps of the threonine pathway from aspartate in Escherichia coli under a single set of experimental conditions chosen to be physiologically relevant. Our aim was to summarize the kinetic behaviour of each enzyme in a single tractable equation that takes into account the effect of the products as competitive inhibitors of the substrates in the forward reaction and also, when appropriate (e.g. near-equilibrium reactions), as substrates of the reverse reactions. Co-operative feedback inhibition by threonine and lysine was also included as necessary. We derived the simplest rate equations that describe the salient features of the enzymes in the physiological range of metabolite concentrations in order to incorporate them ultimately into a complete model of the threonine pathway, able to predict quantitatively the behaviour of the pathway under natural or engineered conditions. (+info)
Threonine synthesis from aspartate in Escherichia coli cell-free extracts: pathway dynamics. (2/46)We have developed an experimental model of the whole threonine pathway that allows us to study the production of threonine from aspartate under different conditions. The model consisted of a desalted crude extract of Escherichia coli to which we added the substrates and necessary cofactors of the pathway: aspartate, ATP and NADPH. In this experimental model we measured not only the production of threonine, but also the time dependence of all the intermediate metabolites and of the initial substrates, aspartate, ATP and NADPH. A stoichiometric conversion of precursors into threonine was observed. We have derived conditions in which a quasi steady state can be transiently observed and used to simulate physiological conditions of functioning of the pathway in the cell. The dependence of threonine synthesis and of the aspartate and NADPH consumption on the initial aspartate and threonine concentrations exhibits greater sensitivity to the aspartate concentration than to the threonine concentration in these non-steady-state conditions. A response to threonine is only observed in a narrow concentration range from 0.23 to 2 mM. (+info)
Control of the threonine-synthesis pathway in Escherichia coli: a theoretical and experimental approach. (3/46)A computer simulation of the threonine-synthesis pathway in Escherichia coli Tir-8 has been developed based on our previous measurements of the kinetics of the pathway enzymes under near-physiological conditions. The model successfully simulates the main features of the time courses of threonine synthesis previously observed in a cell-free extract without alteration of the experimentally determined parameters, although improved quantitative fits can be obtained with small parameter adjustments. At the concentrations of enzymes, precursors and products present in cells, the model predicts a threonine-synthesis flux close to that required to support cell growth. Furthermore, the first two enzymes operate close to equilibrium, providing an example of a near-equilibrium feedback-inhibited enzyme. The predicted flux control coefficients of the pathway enzymes under physiological conditions show that the control of flux is shared between the first three enzymes: aspartate kinase, aspartate semialdehyde dehydrogenase and homoserine dehydrogenase, with no single activity dominating the control. The response of the model to the external metabolites shows that the sharing of control between the three enzymes holds across a wide range of conditions, but that the pathway flux is sensitive to the aspartate concentration. When the model was embedded in a larger model to simulate the variable demands for threonine at different growth rates, it showed the accumulation of free threonine that is typical of the Tir-8 strain at low growth rates. At low growth rates, the control of threonine flux remains largely with the pathway enzymes. As an example of the predictive power of the model, we studied the consequences of over-expressing different enzymes in the pathway. (+info)
Structure of the ask-asd operon and formation of aspartokinase subunits in the cephamycin producer 'Amycolatopsis lactamdurans'. (4/46)The first two genes of the lysine pathway are closely linked forming a transcriptional operon in the cephamycin producer 'Amycolatopsis lactamdurans'. The asd gene, encoding the enzyme aspartic semialdehyde dehydrogenase, has been cloned by complementation of Escherichia coli asd mutants. It encodes a protein of 355 aa with a deduced M(r) of 37109. The ask gene encoding the aspartokinase (Ask) is located upstream of the asd gene as shown by determination of Ask activity conferred to E. coli transformants. asd and ask are separated by 2 nt and are transcribed in a bicistronic 2.6 kb mRNA. As occurs in corynebacteria, the presence of a ribosome-binding site within the ask sequence suggests that this ORF encodes two overlapping proteins, Askalpha of 421 aa and M(r) 44108, and Askbeta of 172 aa and M(r) 18145. The formation of both subunits of Ask from a single gene (ask) was confirmed by using antibodies against the C-terminal end of Ask which is identical in both subunits. Ask activity of 'A. lactamdurans' is regulated by the concerted action of lysine plus threonine and this inhibition is abolished in E. coli transformants containing Ser(301) to Tyr, or Gly(345) to Asp mutations of the 'A. lactamdurans' ask gene. (+info)
A structural basis for the mechanism of aspartate-beta-semialdehyde dehydrogenase from Vibrio cholerae. (5/46)L-Aspartate-beta-semialdehyde dehydrogenase (ASADH) catalyzes the reductive dephosphorylation of beta-aspartyl phosphate to L-aspartate-beta-semialdehyde in the aspartate biosynthetic pathway of plants and micro-organisms. The aspartate pathway produces fully one-quarter of the naturally occurring amino acids, but is not found in humans or other eukaryotic organisms, making ASADH an attractive target for the development of new antibacterial, fungicidal, or herbicidal compounds. We have determined the structure of ASADH from Vibrio cholerae in two states; the apoenzyme and a complex with NADP, and a covalently bound active site inhibitor, S-methyl-L-cysteine sulfoxide. Upon binding the inhibitor undergoes an enzyme-catalyzed reductive demethylation leading to a covalently bound cysteine that is observed in the complex structure. The enzyme is a functional homodimer, with extensive intersubunit contacts and a symmetrical 4-amino acid bridge linking the active site residues in adjacent subunits that could serve as a communication channel. The active site is essentially preformed, with minimal differences in active site conformation in the apoenzyme relative to the ternary inhibitor complex. The conformational changes that do occur result primarily from NADP binding, and are localized to the repositioning of two surface loops located on the rim at opposite sides of the NADP cleft. (+info)
Cloning of dapD, aroD and asd of Leptospira interrogans serovar icterohaemorrhagiae, and nucleotide sequence of the asd gene. (6/46)Metabolites such as diaminopimelate and some aromatic derivatives, not synthesized in mammalian cells, are essential for growth of bacteria. As a first step towards the design of a new human live vaccine that uses attenuated strains of Leptospira interrogans, the asd, aroD and dapD genes, encoding aspartate beta-semialdehyde dehydrogenase, 3-dehydroquinase and tetrahydrodipicolinate N-succinyltransferase, respectively, were cloned by complementation of Escherichia coli mutants. The complete nucleotide sequence of the asd gene was determined and found to contain an open reading frame capable of encoding a protein of 349 amino acids with a calculated Mr of 38,007. Comparison of this deduced L. interrogans aspartate beta-semialdehyde dehydrogenase amino acid sequence with those of the same enzyme from Saccharomyces cerevisiae and Corynebacterium glutamicum revealed 46% and 36% identity, respectively. By contrast, the identity between the L. interrogans enzyme and the Streptococcus mutans or E. coli enzymes was less than 31%. Highly conserved sequences within aspartate semialdehyde dehydrogenase from the five organisms were observed at the amino and carboxyl termini, and around the cysteine of the active site. (+info)
Mechanism of action of an antifungal antibiotic, RI-331, (S) 2-amino-4-oxo-5-hydroxypentanoic acid; kinetics of inactivation of homoserine dehydrogenase from Saccharomyces cerevisiae. (7/46)An antifungal antibiotic (S) 2-amino-4-oxo-5-hydroxypentanoic acid, inhibited the biosynthesis of the aspartate family of amino acids (methionine, isoleucine and threonine) followed by the inhibition of protein biosynthesis in Saccharomyces cerevisiae. This inhibition was effected by impeding the biosynthesis of their common intermediate precursor, homoserine. The inhibition of biosynthesis of homoserine by the antibiotic was attributable to inactivation of homoserine dehydrogenase [EC 188.8.131.52], which is involved in the conversion of aspartate semialdehyde to homoserine in the metabolic pathway leading to threonine, methionine and isoleucine. Since such enzymic activity is not present in animal cells, the selective antifungal activity of the antibiotic is thus explained. (+info)
Capture of an intermediate in the catalytic cycle of L-aspartate-beta-semialdehyde dehydrogenase. (8/46)The structural analysis of an enzymatic reaction intermediate affords a unique opportunity to study a catalytic mechanism in extraordinary detail. Here we present the structure of a tetrahedral intermediate in the catalytic cycle of aspartate-beta-semialdehyde dehydrogenase (ASADH) from Haemophilus influenzae at 2.0-A resolution. ASADH is not found in humans, yet its catalytic activity is required for the biosynthesis of essential amino acids in plants and microorganisms. Diaminopimelic acid, also formed by this enzymatic pathway, is an integral component of bacterial cell walls, thus making ASADH an attractive target for the development of new antibiotics. This enzyme is able to capture the substrates aspartate-beta-semialdehyde and phosphate as an active complex that does not complete the catalytic cycle in the absence of NADP. A distinctive binding pocket in which the hemithioacetal oxygen of the bound substrate is stabilized by interaction with a backbone amide group dictates the R stereochemistry of the tetrahedral intermediate. This pocket, reminiscent of the oxyanion hole found in serine proteases, is completed through hydrogen bonding to the bound phosphate substrate. (+info)
Examples of brain diseases, metabolic, inborn include:
1. Phenylketonuria (PKU): A genetic disorder that affects the body's ability to break down the amino acid phenylalanine, leading to a buildup of toxic substances in the brain and blood.
2. Maple syrup urine disease (MSUD): Another genetic disorder that affects the body's ability to break down certain amino acids, resulting in a distinctive odor in the urine and potential brain damage if left untreated.
3. Mucopolysaccharidoses (MPS): A group of inherited diseases that affect the body's ability to produce or break down certain sugars, leading to progressive damage to various organs and systems, including the brain and nervous system.
4. Fabry disease: An inherited disorder caused by a deficiency of an enzyme called alpha-galactosidase A, which leads to the accumulation of a fatty substance in the body's cells and tissues, including the brain.
5. Mitochondrial disorders: A group of conditions caused by mutations or errors in the DNA of mitochondria, the energy-producing structures within cells. These disorders can affect various organs and systems, including the brain and nervous system.
These conditions are often treated with a combination of dietary restrictions, medication, and other therapies to manage symptoms and prevent complications. In some cases, bone marrow transplantation or enzyme replacement therapy may be necessary. Early detection and intervention can help improve outcomes for individuals with these conditions.
There are several types of inborn errors of amino acid metabolism, including:
1. Phenylketonuria (PKU): This is the most common inborn error of amino acid metabolism and is caused by a deficiency of the enzyme phenylalanine hydroxylase. This enzyme is needed to break down the amino acid phenylalanine, which is found in many protein-containing foods. If phenylalanine is not properly broken down, it can build up in the blood and brain and cause serious health problems.
2. Maple syrup urine disease (MSUD): This is a rare genetic disorder that affects the breakdown of the amino acids leucine, isoleucine, and valine. These amino acids are important for growth and development, but if they are not properly broken down, they can build up in the blood and cause serious health problems.
3. Homocystinuria: This is a rare genetic disorder that affects the breakdown of the amino acid methionine. Methionine is important for the body's production of proteins and other compounds, but if it is not properly broken down, it can build up in the blood and cause serious health problems.
4. Arginase deficiency: This is a rare genetic disorder that affects the breakdown of the amino acid arginine. Arginine is important for the body's production of nitric oxide, a compound that helps to relax blood vessels and improve blood flow.
5. Citrullinemia: This is a rare genetic disorder that affects the breakdown of the amino acid citrulline. Citrulline is important for the body's production of proteins and other compounds, but if it is not properly broken down, it can build up in the blood and cause serious health problems.
6. Tyrosinemia: This is a rare genetic disorder that affects the breakdown of the amino acid tyrosine. Tyrosine is important for the body's production of proteins and other compounds, but if it is not properly broken down, it can build up in the blood and cause serious health problems.
7. Maple syrup urine disease (MSUD): This is a rare genetic disorder that affects the breakdown of the amino acids leucine, isoleucine, and valine. These amino acids are important for growth and development, but if they are not properly broken down, they can build up in the blood and cause serious health problems.
8. PKU (phenylketonuria): This is a rare genetic disorder that affects the breakdown of the amino acid phenylalanine. Phenylalanine is important for the body's production of proteins and other compounds, but if it is not properly broken down, it can build up in the blood and cause serious health problems.
9. Methionine adenosyltransferase (MAT) deficiency: This is a rare genetic disorder that affects the breakdown of the amino acid methionine. Methionine is important for the body's production of proteins and other compounds, but if it is not properly broken down, it can build up in the blood and cause serious health problems.
10. Homocystinuria: This is a rare genetic disorder that affects the breakdown of the amino acid homocysteine. Homocysteine is important for the body's production of proteins and other compounds, but if it is not properly broken down, it can build up in the blood and cause serious health problems.
It is important to note that these disorders are rare and affect a small percentage of the population. However, they can be serious and potentially life-threatening, so it is important to be aware of them and seek medical attention if symptoms persist or worsen over time.
Asd RNA motif
Amino acid synthesis
Malonate-semialdehyde dehydrogenase (acetylating)
Succinic semialdehyde dehydrogenase deficiency
List of MeSH codes (D08)
List of EC numbers (EC 1)
List of EC numbers (EC 2)
List of EC numbers (EC 5)
Citric acid cycle
List of EC numbers (EC 3)
Finding step asd for L-threonine biosynthesis in Desulfovibrio vulgaris Hildenborough
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- ssad, succinic semialdehyde. (revivemedicalny.com)
- Prismane/CO dehydrogenase family [Interproscan]. (ntu.edu.sg)
- The different * steps are catalysed by aspartate kinases I and III (AK I and * AK III), aspartate semialdehyde dehydrogenase (ASD), homoserine * dehydrogenase (HDH), homoserine kinase (HK) and threonine synthase * (TS). (nih.gov)
- The homoserine dehydrogenase encoded by hom in H. campaniensis strain XH26 is responsible for the metabolic shunt of L-aspartate-4-semialdehyde to glycine. (bvsalud.org)
- Model Structure * * ABSTRACT: We have determined the kinetic parameters of the individual * steps of the threonine pathway from aspartate in Escherichia * coli under a single set of experimental conditions chosen to * be physiologically relevant. (nih.gov)
- PubMed ID: 11368768 * * schematic diagram * * [[Image file: chassagnole_2001.png]] * * Threonine-synthesis pathway from aspartate in E. coli. (nih.gov)
- This study aimed to increase ectoine yields by blocking the metabolic shunt pathway of L-aspartate-4-semialdehyde, the precursor substrate in ectoine synthesis. (bvsalud.org)
- An enzyme that catalyzes the conversion of L-aspartate 4-semialdehyde, orthophosphate, and NADP + to yield L-4-aspartyl phosphate and NADPH. (nih.gov)
- Erythrocyte aspartate aminotransferase (EAST) and the EAST activation coefficient are long-term indicators of functional pyridoxine status. (medscape.com)