2. Academic Validation
  3. Histidine triad nucleotide-binding proteins HINT1 and HINT2 share similar substrate specificities and little affinity for the signaling dinucleotide Ap4A

Histidine triad nucleotide-binding proteins HINT1 and HINT2 share similar substrate specificities and little affinity for the signaling dinucleotide Ap4A

  • FEBS Lett. 2020 May;594(10):1497-1505. doi: 10.1002/1873-3468.13745.
Alexander Strom 1,  Cher Ling Tong 2,  Carston R Wagner 1
Affiliations

Affiliations

  • 1 Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA.
  • 2 Department of Biochemistry Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
PMID: 31990367 DOI: 10.1002/1873-3468.13745
Abstract

Human histidine triad nucleotide-binding protein 2 (hHINT2) is an important player in human mitochondrial bioenergetics, but little is known about its catalytic capabilities or its nucleotide phosphoramidate prodrug (proTide)-activating activity akin to the cytosolic isozyme hHINT1. Here, a similar substrate specificity profile (kcat /Km ) for model phosphoramidate substrates was found for hHINT2 but with higher kcat and Km values when compared with hHINT1. A broader pH range for maximum catalytic activity was determined for hHINT2 (pK1 = 6.76 ± 0.16, pK2 = 8.41 ± 0.07). In addition, the known hHINT1-microphthalmia-inducing transcription factor-regulating molecule Ap4 A was found to have no detectable binding to HINT1 nor HINT2 by isothermal titration calorimetry. These results demonstrate that despite differences in their sequence and localization, HINT1 and HINT2 have similar nucleotide substrate specificities, which should be considered in future proTide design and in studies of their natural function.

Keywords

Ap4A; hHINT1; hHINT2; pH profile; phosphoramidate; proTide; substrate specificity.

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