| First Author | Donini S | Year | 2006 |
| Journal | Biochem Biophys Res Commun | Volume | 350 |
| Issue | 4 | Pages | 922-8 |
| PubMed ID | 17034760 | Mgi Jnum | J:115003 |
| Mgi Id | MGI:3690523 | Doi | 10.1016/j.bbrc.2006.09.112 |
| Citation | Donini S, et al. (2006) A threonine synthase homolog from a mammalian genome. Biochem Biophys Res Commun 350(4):922-8 |
| abstractText | The genomes of several vertebrates contain two genes encoding proteins highly similar to threonine synthase (TS), even though the biosynthesis of l-threonine (l-Thr) is not known to occur in these animals. We report a bioinformatic analysis of the two TS-like genes, the recombinant expression of one murine TS homolog (mTSH2) and its initial biochemical characterization. Recombinant mTSH2 contained bound pyridoxal-5'-phosphate (PLP), but did not synthesize l-Thr. The enzyme did, however, bind O-phospho-homoserine (PHS; the actual TS substrate) and degraded it to alpha-ketobutyrate, phosphate, and ammonia-a known side reaction of microbial TSs. mTSH2 also degraded O-phospho-threonine (PThr) to alpha-ketobutyrate, showing that it can act as a catabolic phospho-lyase on both gamma- and beta-phosphorylated substrates. These findings suggest an unusual evolutionary origin for mTSH2, whereby an original TS enzyme became 'recycled' into a phospho-lyase upon dismissal, in metazoa, of the l-Thr biosynthetic pathway. |
