کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1938306 | 1536792 | 2006 | 7 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: A threonine synthase homolog from a mammalian genome A threonine synthase homolog from a mammalian genome](/preview/png/1938306.png)
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 α-ketobutyrate, phosphate, and ammonia—a known side reaction of microbial TSs. mTSH2 also degraded O-phospho-threonine (PThr) to α-ketobutyrate, showing that it can act as a catabolic phospho-lyase on both γ- and β-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.
Journal: Biochemical and Biophysical Research Communications - Volume 350, Issue 4, 1 December 2006, Pages 922–928