Download MendeleyStructural insights on mouse l-threonine dehydrogenase: A regulatory role of Arg180 in catalysis
He, C., Huang, X., Liu, Y., Li, F., Yang, Y., Tao, H., Han, C., Zhao, C., Xiao, Y., Shi, Y.(2015) J Struct Biol 192: 510-518
- PubMed: 26492815
- DOI: https://doi.org/10.1016/j.jsb.2015.10.014
- Primary Citation of Related Structures:
4YR9, 4YRA, 4YRB - PubMed Abstract:
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.
Organizational Affiliation:
Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis and School of Life Sciences, Anhui University, Hefei, Anhui 230601, China. Electronic address: chaohe@ahu.edu.cn.
