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Molecular cloning and tissue distribution of mammalian L-threonine 3-dehydrogenases.

Edgar AJ - BMC Biochem. (2002)

Bottom Line: These eukaryotic L-threonine dehydrogenases also have significant similarity with the prokaryote L-threonine dehydrogenase amino-terminus peptide sequence of the bacterium, Clostridium sticklandii.The first cloning of transcripts for L-threonine dehydrogenase from eukaryotic organisms are reported.However, they do not have any significant sequence homology to the well-characterised Escherichia coli L-threonine dehydrogenase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Tissue Engineering and Regenerative Medicine Centre, Division of Investigative Science, Faculty of Medicine, Imperial College of Science, Technology and Medicine, Chelsea & Westminster Hospital, London, United Kingdom. alasdair.edgar@ic.ac.uk

ABSTRACT

Background: In mammals, L-threonine is an indispensable amino acid. The conversion of L-threonine to glycine occurs through a two-step biochemical pathway involving the enzymes L-threonine 3-dehydrogenase and 2-amino-3-ketobutyrate coenzyme A ligase. The L-threonine 3-dehydrogenase enzyme has been purified and characterised, but the L-threonine 3-dehydrogenase gene has not previously been identified in mammals.

Results: Transcripts for L-threonine 3-dehydrogenase from both the mouse and pig are reported. The ORFs of both L-threonine dehydrogenase cDNAs encode proteins of 373 residues (41.5 kDa) and they share 80% identity. The mouse gene is located on chromosome 14, band C. The amino-terminal regions of these proteins have characteristics of a mitochondrial targeting sequence and are related to the UDP-galactose 4-epimerases, with both enzyme families having an amino-terminal NAD+ binding domain. That these cDNAs encode threonine dehydrogenases was shown, previously, by tiling 13 tryptic peptide sequences, obtained from purified L-threonine dehydrogenase isolated from porcine liver mitochondria, on to the pig ORF. These eukaryotic L-threonine dehydrogenases also have significant similarity with the prokaryote L-threonine dehydrogenase amino-terminus peptide sequence of the bacterium, Clostridium sticklandii. In murine tissues, the expression of both L-threonine dehydrogenase and 2-amino-3-ketobutyrate coenzyme A ligase mRNAs were highest in the liver and were also present in brain, heart, kidney, liver, lung, skeletal muscle, spleen and testis.

Conclusions: The first cloning of transcripts for L-threonine dehydrogenase from eukaryotic organisms are reported. However, they do not have any significant sequence homology to the well-characterised Escherichia coli L-threonine dehydrogenase.

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Comparison of murine and prokaryotic L-threonine dehydrogenase protein sequences. The L-threonine dehydrogenase sequences are: mouse, MmTDH; Staphylococcus aureus hypothetical protein from gene SAV0542 (accession No. BAB46113) [19], S. aureus; Clostridium sticklandii threonine dehydrogenase amino-terminal peptide, C.sticklandii NT [15].
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Figure 6: Comparison of murine and prokaryotic L-threonine dehydrogenase protein sequences. The L-threonine dehydrogenase sequences are: mouse, MmTDH; Staphylococcus aureus hypothetical protein from gene SAV0542 (accession No. BAB46113) [19], S. aureus; Clostridium sticklandii threonine dehydrogenase amino-terminal peptide, C.sticklandii NT [15].

Mentions: That L-threonine dehydrogenase sequences have been evolutionarily conserved between the Gram+ bacteria and mammals is shown by the homology between mouse and the amino-terminus peptide sequence from the threonine dehydrogenase of the Gram+ Firmicutes bacteria, C. sticklandii which has 54% identity and 93% similarity over 28 residues [15] (Fig. 6). C. sticklandii is an amino acid fermenting anaerobic bacterium that can grow on threonine as a sole substrate. Together, the mouse and C. sticklandii sequences enabled the identification of putative L-threonine dehydrogenase genes in a number of bacterial species such as Thermoplasma acidophilum, T. volcanium and Staphylococcus epidermidis. An alignment with the putative L-threonine dehydrogenase sequence, the SAV0542 gene, from S. aureus [19] that has 41% identity and 75% similarity to the mouse protein is shown in Fig. 6.


Molecular cloning and tissue distribution of mammalian L-threonine 3-dehydrogenases.

Edgar AJ - BMC Biochem. (2002)

Comparison of murine and prokaryotic L-threonine dehydrogenase protein sequences. The L-threonine dehydrogenase sequences are: mouse, MmTDH; Staphylococcus aureus hypothetical protein from gene SAV0542 (accession No. BAB46113) [19], S. aureus; Clostridium sticklandii threonine dehydrogenase amino-terminal peptide, C.sticklandii NT [15].
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC117216&req=5

Figure 6: Comparison of murine and prokaryotic L-threonine dehydrogenase protein sequences. The L-threonine dehydrogenase sequences are: mouse, MmTDH; Staphylococcus aureus hypothetical protein from gene SAV0542 (accession No. BAB46113) [19], S. aureus; Clostridium sticklandii threonine dehydrogenase amino-terminal peptide, C.sticklandii NT [15].
Mentions: That L-threonine dehydrogenase sequences have been evolutionarily conserved between the Gram+ bacteria and mammals is shown by the homology between mouse and the amino-terminus peptide sequence from the threonine dehydrogenase of the Gram+ Firmicutes bacteria, C. sticklandii which has 54% identity and 93% similarity over 28 residues [15] (Fig. 6). C. sticklandii is an amino acid fermenting anaerobic bacterium that can grow on threonine as a sole substrate. Together, the mouse and C. sticklandii sequences enabled the identification of putative L-threonine dehydrogenase genes in a number of bacterial species such as Thermoplasma acidophilum, T. volcanium and Staphylococcus epidermidis. An alignment with the putative L-threonine dehydrogenase sequence, the SAV0542 gene, from S. aureus [19] that has 41% identity and 75% similarity to the mouse protein is shown in Fig. 6.

Bottom Line: These eukaryotic L-threonine dehydrogenases also have significant similarity with the prokaryote L-threonine dehydrogenase amino-terminus peptide sequence of the bacterium, Clostridium sticklandii.The first cloning of transcripts for L-threonine dehydrogenase from eukaryotic organisms are reported.However, they do not have any significant sequence homology to the well-characterised Escherichia coli L-threonine dehydrogenase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Tissue Engineering and Regenerative Medicine Centre, Division of Investigative Science, Faculty of Medicine, Imperial College of Science, Technology and Medicine, Chelsea & Westminster Hospital, London, United Kingdom. alasdair.edgar@ic.ac.uk

ABSTRACT

Background: In mammals, L-threonine is an indispensable amino acid. The conversion of L-threonine to glycine occurs through a two-step biochemical pathway involving the enzymes L-threonine 3-dehydrogenase and 2-amino-3-ketobutyrate coenzyme A ligase. The L-threonine 3-dehydrogenase enzyme has been purified and characterised, but the L-threonine 3-dehydrogenase gene has not previously been identified in mammals.

Results: Transcripts for L-threonine 3-dehydrogenase from both the mouse and pig are reported. The ORFs of both L-threonine dehydrogenase cDNAs encode proteins of 373 residues (41.5 kDa) and they share 80% identity. The mouse gene is located on chromosome 14, band C. The amino-terminal regions of these proteins have characteristics of a mitochondrial targeting sequence and are related to the UDP-galactose 4-epimerases, with both enzyme families having an amino-terminal NAD+ binding domain. That these cDNAs encode threonine dehydrogenases was shown, previously, by tiling 13 tryptic peptide sequences, obtained from purified L-threonine dehydrogenase isolated from porcine liver mitochondria, on to the pig ORF. These eukaryotic L-threonine dehydrogenases also have significant similarity with the prokaryote L-threonine dehydrogenase amino-terminus peptide sequence of the bacterium, Clostridium sticklandii. In murine tissues, the expression of both L-threonine dehydrogenase and 2-amino-3-ketobutyrate coenzyme A ligase mRNAs were highest in the liver and were also present in brain, heart, kidney, liver, lung, skeletal muscle, spleen and testis.

Conclusions: The first cloning of transcripts for L-threonine dehydrogenase from eukaryotic organisms are reported. However, they do not have any significant sequence homology to the well-characterised Escherichia coli L-threonine dehydrogenase.

Show MeSH
Related in: MedlinePlus