| First Author | He C | Year | 2015 |
| Journal | J Struct Biol | Volume | 192 |
| Issue | 3 | Pages | 510-8 |
| PubMed ID | 26492815 | Mgi Jnum | J:242529 |
| Mgi Id | MGI:5905531 | Doi | 10.1016/j.jsb.2015.10.014 |
| Citation | He C, et al. (2015) Structural insights on mouse L-threonine dehydrogenase: A regulatory role of Arg180 in catalysis. J Struct Biol 192(3):510-8 |
| abstractText | Mouse L-threonine dehydrogenase (mTDH), which belongs to the short-chain dehydrogenase/reductase (SDR) superfamily and mediates threonine catabolism, plays pivotal roles in both powerful biosynthesis and signaling in mouse stem cells and has a regulatory residue Arg180. Here we determined three crystal structures of mTDH: wild-type (WT) in the apo form; in complex with NAD(+) and a substrate analog, glycerol, or with only NAD(+); as well as the R180K variant with NAD(+). This is the first description of a structure for mammalian SDR-type TDH. Structural comparison revealed the structural basis for SDR-type TDH catalysis remains strictly conserved in bacteria and mammals. Kinetic enzyme assays, and isothermal titration calorimetry (ITC) measurements indicated the R180K mutation has little effect on NAD(+) binding affinity, whereas affects the substrate's affinity for the enzyme. The crystal structure of R180K with NAD(+), biochemical and spectroscopic studies suggested that the R180K mutant should bind NAD(+) in a similar way and have a similar folding to the WT. However, the R180K variant may have difficulty adopting the closed form due to reduced interaction of residue 180 with a loop which connects a key position for mTDH switching between the closed and open forms in mTDH catalysis, and thereby exhibited a significantly decreased kcat/Km value toward the substrate, L-Thr. In sum, our results suggest that activity of GalE-like TDH can be regulated by remote interaction, such as hydrogen bonding and hydrophobic interaction around the Arg180 of mTDH. |
