Hydroaromatic Equilibration During Biosynthesis of Shikimic Acid

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• 作者：David R. Knop ; K. M. Draths ; Sunil S. Chandran ; Jessica L. Barker ; Ralph von Daeniken ; Wolfgang Weber ; and J. W. Frost
• 刊名：Journal of the American Chemical Society
• 出版年：2001
• 出版时间：October 24, 2001
• 年：2001
• 卷：123
• 期：42
• 页码：10173 - 10182
• 全文大小：134K
• 年卷期：v.123,no.42(October 24, 2001)
• ISSN：1520-5126

文摘

The expense and limited availability of shikimic acid isolated from plants has impeded utilizationof this hydroaromatic as a synthetic starting material. Although recombinant Escherichia coli catalysts havebeen constructed that synthesize shikimic acid from glucose, the yield, titer, and purity of shikimic acid arereduced by the sizable concentrations of quinic acid and 3-dehydroshikimic acid that are formed as byproducts.The 28.0 g/L of shikimic acid synthesized in 14% yield by E. coli SP1.1/pKD12.138 in 48 h as a 1.6:1.0:0.65(mol/mol/mol) shikimate/quinate/dehydroshikimate mixture is typical of synthesized product mixtures. Quinicacid formation results from the reduction of 3-dehydroquinic acid catalyzed by aroE-encoded shikimatedehydrogenase. Is quinic acid derived from reduction of 3-dehydroquinic acid prior to synthesis of shikimicacid? Alternatively, does quinic acid result from a microbe-catalyzed equilibration involving transport of initiallysynthesized shikimic acid back into the cytoplasm and operation of the common pathway of aromatic aminoacid biosynthesis in the reverse of its normal biosynthetic direction? E. coli SP1.1/pSC5.214A, a constructincapable of de novo synthesis of shikimic acid, catalyzed the conversion of shikimic acid added to its culturemedium into a 1.1:1.0:0.70 molar ratio of shikimate/quinate/dehydroshikimate within 36 h. Further mechanisticinsights were afforded by elaborating the relationship between transport of shikimic acid and formation ofquinic acid. These experiments indicate that formation of quinic acid during biosynthesis of shikimic acidresults from a microbe-catalyzed equilibration of initially synthesized shikimic acid. By apparently repressingshikimate transport, the aforementioned E. coli SP1.1/pKD12.138 synthesized 52 g/L of shikimic acid in 18%yield from glucose as a 14:1.0:3.0 shikimate/quinate/dehydroshikimate mixture.