Discovery of an l-Fucono-1,5-lactonase from cog3618 of the Amidohydrolase Superfamily

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• 作者：Merlin Eric Hobbs ; Matthew Vetting ; Howard J. Williams ; Tamari Narindoshvili ; Devon M. Kebodeaux ; Brandan Hillerich ; Ronald D. Seidel ; Steven C. Almo ; Frank M. Raushel
• 刊名：Biochemistry
• 出版年：2013
• 出版时间：January 8, 2013
• 年：2013
• 卷：52
• 期：1
• 页码：239-253
• 全文大小：705K
• 年卷期：v.52,no.1(January 8, 2013)
• ISSN：1520-4995

文摘

A member of the amidohydrolase superfamily, BmulJ_04915 from Burkholderia multivorans, of unknown function was determined to hydrolyze a series of sugar lactones: l-fucono-1,4-lactone, d-arabino-1,4-lactone, l-xylono-1,4-lactone, d-lyxono-1,4-lactone, and l-galactono-1,4-lactone. The highest activity was shown for l-fucono-1,4-lactone with a k_cat value of 140 s^鈥? and a k_cat/K_m value of 1.0 脳 10⁵ M^鈥? s^鈥? at pH 8.3. The enzymatic product of an adjacent l-fucose dehydrogenase, BmulJ_04919, was shown to be l-fucono-1,5-lactone via nuclear magnetic resonance spectroscopy. l-Fucono-1,5-lactone is unstable and rapidly converts nonenzymatically to l-fucono-1,4-lactone. Because of the chemical instability of l-fucono-1,5-lactone, 4-deoxy-l-fucono-1,5-lactone was enzymatically synthesized from 4-deoxy-l-fucose using l-fucose dehydrogenase. BmulJ_04915 hydrolyzed 4-deoxy-l-fucono-1,5-lactone with a k_cat value of 990 s^鈥? and a k_cat/K_m value of 8.0 脳 10⁶ M^鈥? s^鈥? at pH 7.1. The protein does not require divalent cations in the active site for catalytic activity. BmulJ_04915 is the second enzyme from cog3618 of the amidohydrolase superfamily that does not require a divalent metal for catalytic activity. BmulJ_04915 is the first enzyme that has been shown to catalyze the hydrolysis of either l-fucono-1,4-lactone or l-fucono-1,5-lactone. The structures of the fuconolactonase and the fucose dehydrogenase were determined by X-ray diffraction methods.