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Mechanistic insights into 1-deoxy-d-xylulose 5-phosphate reductoisomerase, a key enzyme of the MEP terpenoid biosynthetic pathway

Authors

  • Heng Li,

    1. Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), College of Life Sciences, Northwest University, Xi'an, China
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  • Jie Tian,

    1. Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), College of Life Sciences, Northwest University, Xi'an, China
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  • Wei Sun,

    1. Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), School of Chemistry and Materials Science, Northwest University, Xi'an, China
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  • Wei Qin,

    1. Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), College of Life Sciences, Northwest University, Xi'an, China
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  • Wen-Yun Gao

    Corresponding author
    1. Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), College of Life Sciences, Northwest University, Xi'an, China
    • Correspondence

      W.-Y. Gao, Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), College of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China

      Fax: +86 29 88303572

      Tel: +86 29 88303446 ext. 832

      E-mail: gaowenyun@nwu.edu.cn

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Abstract

The binding mode of 1-deoxy-d-xylulose 5-phosphate (DXP) to 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) (EC 1.1.1.267) from Escherichia coli was investigated via 18O isotope exchange experiments and determination of the kinetic parameters of the reaction. The results support a C3–C4 substrate binding mode in which DXP chelates a DXR-bound divalent cation via its hydroxyl groups at C3 and C4. Based on this binding mode and the early results, a catalytic cycle for the conversion of DXP to 2-methyl-d-erythritol 4-phosphate mediated by DXR including a pseudo-single molecule transition state of the retro-aldol intermediates is proposed. Taking into account the binding mode of DXP and the catalytic cycle of DXR, the mechanistic insights of DXR are disclosed and the current discrepancies concerning the catalysis of this enzyme are interpreted within the accepted retro-aldol/aldol sequence.

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