Structural insights into the enzyme specificity of a novel ω-transaminase from the thermophilic bacterium Sphaerobacter thermophilus

Sunghark Kwon, Jun Hyuck Lee, Chang Min Kim, Hyun Ji Ha, Sung Hoon Lee, Chang Sup Lee, Ju Hong Jeon, Insuk So, Hyun Ho Park

Research output: Contribution to journalArticlepeer-review

Abstract

Transaminases are pyridoxal 5′-phosphate-dependent enzymes that reversibly catalyze transamination reactions from an amino group donor substrate to an amino group acceptor substrate. ω-Transaminases (ωTAs) utilize compounds with an amino group not at α-carbon position as their amino group donor substrates. Recently, a novel ωTA with broad substrate specificity and high thermostability from the thermophilic bacterium Sphaerobacter thermophilus (St-ωTA) has been reported. Although St-ωTA has been biochemically characterized, little is known about its determinants of substrate specificity. In the present study, we determined the crystal structure of St-ωTA at 1.9 Å resolution to clarify in detail its mechanism of substrate recognition. The structure of St-ωTA revealed that it has a voluminous active site resulting from the unique spatial arrangement of residues comprising its active site. In addition, our molecular docking simulation results suggest that substrate compounds may bind to active site residues via electrostatic interactions or hydrophobic interactions that can be induced by subtle rearrangements of active site residues. On the basis of these structural analyses, we propose a plausible working model of the enzymatic mechanism of St-ωTA. Our results provide profound structural insights into the substrate specificity of St-ωTA and extend the boundaries of knowledge of TAs.

Original languageEnglish
Article number107395
JournalJournal of Structural Biology
Volume208
Issue number3
DOIs
StatePublished - 1 Dec 2019

Keywords

  • Pyridoxal 5′-phosphate
  • Sphaerobacter thermophilus
  • Substrate specificity
  • Thermostability
  • ω-Transaminase

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