Disease relevance of threonine

• The 987-base-pair coding region of the tdc gene of Escherichia coli K-12 encoding biodegradative threonine dehydratase [Tdc; L-threonine hydro-lyase (deaminating), EC 4.2.1.16], previously cloned in this laboratory, was sequenced [1].
• Incubation of Rhodospirillum rubrum homoserine dehydrogenase (L-homoserine:NAD+ oxidoreductase, EC 1.1.1.3) with p-mercuribenzoate (PMB) in the presence of 0.2 M KCl and 2 mM L-threonine resulted in complete loss of enzyme activity [2].
• Two different pyridoxal 5'-phosphate-containing l-threonine deaminases (EC 4.3.1.19), biosynthetic and biodegradative, which catalyze the deamination of l-threonine to alpha-ketobutyrate, are present in Escherichia coli and Salmonella typhimurium [3].
• Mean weight loss in the placebo group was 1.1 kg and in the L-threonine group was 3.2 kg; the BCAA group gained 0.2 kg (p = 0.04) [4].
• The inducibly formed L-threonine 3-dehydrogenase, purified from Corynebacterium sp. B6 to a specific activity of about 30-35 mumol of product formed/min per mg of protein, exhibited a sigmoid kinetic response to substrate concentration [5].

Psychiatry related information on threonine

• Since several substances which increase the motor activity of the gastrointestinal tract may produce effects on the intestinal absorption of nutrients, the present study has been carried out to determine whether erythromycin affects the L-threonine intestinal absorption [6].

High impact information on threonine

• Structural basis for double-sieve discrimination of L-valine from L-isoleucine and L-threonine by the complex of tRNA(Val) and valyl-tRNA synthetase [7].
• CHA1 of Saccharomyces cerevisiae is the gene for the catabolic L-serine (L-threonine) dehydratase, which is responsible for biodegradation of serine and threonine [8].
• The differences observed in the tertiary and quaternary structures of TdcB in the absence and presence of CMP appear to account for enzyme activation and increased binding affinity for l-threonine [3].
• The enzyme also catalyzes water alpha,beta-elimination with L-serine and L-threonine. alpha,beta-Elimination with these substrates is observed both in vitro and in vivo [9].
• The increase in sigmoidal kinetics for the mutants relative to wild-type threonine deaminase may be attributable to the elimination of L-threonine binding to the effector sites, which activates the wild-type enzyme [10].

Chemical compound and disease context of threonine

• The introduction of a plasmid carrying the aspartokinase II gene into an auxotrophic Escherichia coli strain lacking all three aspartokinases restored its ability to grow in the absence of L-lysine, L-threonine, and L-methionine [11].
• L-Threonine dehydrogenase, which catalyzes the conversion of L-threonine to aminoacetone + CO2 presumably via the intermediate formation of alpha-amino-beta-ketobutyrate, has been purified to apparent homogeneity from extracts of a mutant of Escherichia coli K-12 which has constitutively derepressed levels of the enzyme [12].
• D-1-Amino-2-propanol:NAD+ oxidoreductase activity, which catalyzes the second step in a pathway wherein L-threonine is converted to D-1-amino-2-propanol via the intermediate formation of aminoacetone, has been purified 500-fold from Escherichia coli K-12 [13].
• Evidence for L-threonine cleavage and allothreonine formation by different enzymes from Clostridium pasteurianum: threonine aldolase and serine hydroxymethyltransferase [14].
• Bacterial catabolism of threonine. Threonine degradation initiated by L-threonine acetaldehyde-lyase (aldolase) in species of Pseudomonas [15].

Biological context of threonine

• This alkylated protein retains eight binding sites for L-threonine [16].
• Comparison of kinetics parameters in the presence and absence of a Na+ gradient suggests that both partially and fully loaded forms of the carrier can function to translocate substrate and that Na+ serves to accelerate L-threonine transport by a mechanism that does not involve enhanced substrate binding [17].
• The single mutation in strain CU18 results in altered regulation of ilv gene expression and in the production of an altered L-threonine deaminase [18].
• The autoregulatory model specifies that L-threonine deaminase participates in the control of the expression of the ilv ADE gene cluster as well as the ilv B gene and ilv C gene, which constitute three separate units of regulation [18].
• The influx of L-threonine through system ASC does not influence the membrane potential in cultured human fibroblasts although comparable fluxes of amino acids through another Na(+)-dependent agency, system A, effectively depolarize the cells [19].

Anatomical context of threonine

• These data indicate that the transport system available for L-threonine in the intestinal brush border membrane (system B) is functionally distinct from other amino acid transport systems [17].
• L-Threonine dehydrogenase (L-threonine:NAD+ oxidoreductase (EC 1.1.1.103) has been purified to apparent homogeneity from chicken liver mitochondria [20].
• Biochemical analysis reveals that protein kinase C autophosphorylates on S660, that autophosphorylation on S660 follows T641 autophosphorylation, that autophosphorylation on S660 is accompanied by the release of protein kinase C into the cytosol, and that T500 is not an autophosphorylation site [21].
• L-threonine transport in pig jejunal brush border membrane vesicles. Functional characterization of the unique system B in the intestinal epithelium [17].
• Expression of SATT cDNA in HeLa cells induced stereospecific uptake of L-serine, L-alanine, and L-threonine that was not inhibited by excess (3 mM) 2-(methylamino)-isobutyric acid, a specific substrate for the System A amino acid transporter [22].

Associations of threonine with other chemical compounds

• This ligase, which catalyzes the cleavage/condensation reaction between 2-amino-3-ketobutyrate (the presumed product of the L-threonine dehydrogenase-catalyzed reaction) and glycine + acetyl-CoA, has an apparent molecular weight approximately equal to 85,000 and consists of two identical (or nearly identical) subunits with Mr = 42,000 [23].
• By monitoring culture supernatants from various mutants using 1H nuclear magnetic resonance (NMR), we followed the anaerobic conversion of L-threonine to propionate [24].
• Threonine synthase (TS), the last enzyme of the threonine biosynthetic pathway, catalyzes L-threonine formation from L-homoserine phosphate (HSerP; Km = 0.5 mM, V = 440 min-1) and DL-vinylglycine [25].
• Threonine is catabolized by L-threonine 3-dehydrogenase and threonine dehydratase in hepatocytes from domestic cats (Felis domestica) [26].
• In this way, the SHMT activity in an L-threonine producer was reduced to 8% of the initial activity, which led to a 41% reduction in glycine, while L-threonine was simultaneously increased by 49% [27].
• Mutation of the corresponding residue (Thr-211) in Kv3.1 to alanine also caused intracellular retention, suggesting that the conserved threonine plays a generalized role in surface expression [28].
• These results demonstrate that mutation of the gatekeeper threonine is a common mechanism of activation for tyrosine kinases and provide structural insights to guide the development of next-generation inhibitors [29].
• We used a combination of phosphopeptide enrichment and mass spectrometry to enrich and identify serine (S) and threonine (T) phosphopeptides of GBS [30].

Gene context of threonine

• Genetic regulation of the ilvGMEDA cluster involves attenuation, internal promoters, internal Rho-dependent termination sites, a site of polarity in the ilvG pseudogene of the wild-type organism, and autoregulation by the ilvA gene product, the biosynthetic L-threonine deaminase [31].
• Genes encoding the mitochondrial (SHM1) and cytosolic (SHM2) serine hydroxymethyltransferases, and the L-threonine aldolase gene (GLY1) from Candida albicans were cloned and sequenced [32].
• Concerning the polymorphism within exon 8 of the LDL receptor (alanin/threonin), there was also a predominance of the allele carrying threonin in the index group, which barely missed significance [33].
• L-serine dehydratase (SDH), a member of the beta-family of pyridoxal phosphate-dependent (PLP) enzymes, catalyzes the deamination of L-serine and L-threonine to yield pyruvate or 2-oxobutyrate [34].
• Genetic and biochemical analyses with plasmids harboring mutations in the anaerobically expressed tdcABC operon indicated that the tdcC gene product was responsible for L-threonine uptake [35].

Analytical, diagnostic and therapeutic context of threonine

• Even though the remaining dehydrogenase activity is no longer inhibited by L-threonine, ultrafiltration binding studies and far-UV CD spectra clearly demonstrate that one of the two sets of inhibitor-binding sites is still intact [36].
• To assess whether other 5-HT1 receptors would behave similarly, we have used site-directed mutagenesis to replace the T or A in 5-HT1D alpha, 5-HT1E and 5-HT1F receptors with N [37].
• Furthermore, two significant mutations, thrA345 and ilvA97, which are essential for overproduction of L-threonine, were identified in TF5015 by the sequence analysis [38].
• Sequence alignment reveals that the yeast enzyme is the smallest homoserine dehydrogenase known, owing to the absence of a C-terminal domain endowed with the L-threonine allosteric response in Gram positive bacteria [39].
• The XbaI polymorphism at the apoB locus, which involves the third base of threonin codon 2488 (ACC-->ACT) without changing the amino acid sequence was examined in a case-control study comprising 238 survivors of myocardial infarction (MI) and 621 controls [40].

References