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Structural insights on mouse l-threonine dehydrogenase: A regulatory role of Arg180 in catalysis.
- Source :
-
Journal of Structural Biology . Dec2015, Vol. 192 Issue 3, p510-518. 9p. - Publication Year :
- 2015
-
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 k cat / K m 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. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10478477
- Volume :
- 192
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Journal of Structural Biology
- Publication Type :
- Academic Journal
- Accession number :
- 110944796
- Full Text :
- https://doi.org/10.1016/j.jsb.2015.10.014