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Open AccessArticle

Crystal Structure of IlvC, a Ketol-Acid Reductoisomerase, from Streptococcus Pneumoniae

1
Departments of Biological Sciences, Sungkyunkwan University, 2066 Seobu-ro, Suwon 16419, Korea
2
Departments of Chemistry, Sungkyunkwan University, 2066 Seobu-ro, Suwon 16419, Korea
3
Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
*
Author to whom correspondence should be addressed.
Crystals 2019, 9(11), 551; https://doi.org/10.3390/cryst9110551
Received: 8 October 2019 / Revised: 22 October 2019 / Accepted: 23 October 2019 / Published: 24 October 2019
(This article belongs to the Special Issue Crystallographic Studies of Enzymes)
Biosynthesis of branched-chain amino acids (BCAAs), including isoleucine, leucine and valine, is required for survival and virulence of a bacterial pathogen such as Streptococcus pneumoniae. IlvC, a ketol-acid reductoisomerase (E.C. 1.1.1.86) with NADP(H) and Mg2+ as cofactors from the pathogenic Streptococcus pneumoniae (SpIlvC), catalyzes the second step in the BCAA biosynthetic pathway. To elucidate the structural basis for the IlvC-mediated reaction, we determined the crystal structure of SpIlvC at 1.69 Å resolution. The crystal structure of SpIlvC contains an asymmetric dimer in which one subunit is in apo-form and the other in NADP(H) and Mg2+-bound form. Crystallographic analysis combined with an activity assay and small-angle X-ray scattering suggested that SpIlvC retains dimeric arrangement in solution and that D83 in the NADP(H) binding site and E195 in the Mg2+ binding site are the most critical in the catalytic activity of SpIlvC. Crystal structures of SpIlvC mutants (R49E, D83G, D191G and E195S) revealed local conformational changes only in the NADP(H) binding site. Taken together, our results establish the molecular mechanism for understanding functions of SpIlvC in pneumococcal growth and virulence. View Full-Text
Keywords: IlvC; Streptococcus pneumoniae; BCAA pathway; ketol-acid reductoisomerase IlvC; Streptococcus pneumoniae; BCAA pathway; ketol-acid reductoisomerase
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MDPI and ACS Style

Kim, G.; Shin, D.; Lee, S.; Yun, J.; Lee, S. Crystal Structure of IlvC, a Ketol-Acid Reductoisomerase, from Streptococcus Pneumoniae. Crystals 2019, 9, 551. https://doi.org/10.3390/cryst9110551

AMA Style

Kim G, Shin D, Lee S, Yun J, Lee S. Crystal Structure of IlvC, a Ketol-Acid Reductoisomerase, from Streptococcus Pneumoniae. Crystals. 2019; 9(11):551. https://doi.org/10.3390/cryst9110551

Chicago/Turabian Style

Kim, Gyuhee; Shin, Donghyuk; Lee, Sumin; Yun, Jaesook; Lee, Sangho. 2019. "Crystal Structure of IlvC, a Ketol-Acid Reductoisomerase, from Streptococcus Pneumoniae" Crystals 9, no. 11: 551. https://doi.org/10.3390/cryst9110551

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