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Crystal structure of α-acetolactate decarboxylase from Bacillus subtilis subspecies spizizenii
Korean J. Microbiol 2019;55(1):9-16
Published online March 31, 2019
© 2019 The Microbiological Society of Korea.

Jiyoung Eom1†, Han Byeol Oh1†, and Sung-il Yoon1,2*

1Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon 24341, Republic
of Korea, 2Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon 24341, Republic of Korea
Correspondence to: E-mail:; Tel.: +82-33-250-8385; Fax: +82-33-259-5643
Received January 7, 2019; Accepted January 29, 2019.
Acetoin is generated by numerous microorganisms using α-acetolactate decarboxylase (ALDC) to prevent overacidification of cells and their environment and to store remaining energy. Because acetoin has been used as a safe flavor enhancer in food products, industries have been interested in biotechnological production of acetoin using ALDC. ALDC is a metal-dependent enzyme that produces acetoin from α-acetolactate through decarboxylation reaction. Here, we report the crystal structure of ALDC from Bacillus subtilis subspecies spizizenii (bssALDC) at 1.7 Å resolution. bssALDC folds into a two-domain α/β structure where two β-sheets form a central core. bssALDC assembles into a dimer through central hydrophobic interactions and peripheral hydrophilic interactions. bssALDC coordinates a zinc ion using three histidine residues and three water molecules. Based on comparative analyses of ALDC structures and sequences, we propose that the active site of bssALDC includes the zinc ion and its neighboring bssALDC residues.
Keywords : Bacillus subtilis, acetoin, α-acetolactate decarboxylase, structure, zinc

March 2019, 55 (1)
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