Characterization of the 2-Phospho-L-lactate Transferase Enzyme Involved in Coenzyme F420 Biosynthesis in Methanococcus jannaschii

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• 作者：Marion Graupner ; Huimin Xu ; and Robert H. White
• 刊名：Biochemistry
• 出版年：2002
• 出版时间：March 19, 2002
• 年：2002
• 卷：41
• 期：11
• 页码：3754 - 3761
• 全文大小：169K
• 年卷期：v.41,no.11(March 19, 2002)
• ISSN：1520-4995

文摘

The protein product of the Methanococcus jannaschii MJ1256 gene has been expressed inEscherichia coli, purified to homogeneity, and shown to be involved in coenzyme F₄₂₀ biosynthesis. Theprotein catalyzes the transfer of the 2-phospholactate moiety from lactyl (2) diphospho-(5')guanosine(LPPG) to 7,8-didemethyl-8-hydroxy-5-deazariboflavin (Fo) with the formation of the L-lactyl phosphodiester of 7,8-didemethyl-8-hydroxy-5-deazariboflavin (F₄₂₀-0) and GMP. On the basis of the reactioncatalyzed, the enzyme is named LPPG:Fo 2-phospho-L-lactate transferase. Since the reaction is the fourthstep in the biosynthesis of coenzyme F₄₂₀, the enzyme has been designated as CofD, the product of thecofD gene. The transferase requires Mg²⁺ for activity, and the catalysis does not appear to proceed via acovalent intermediate. To a lesser extent CofD also catalyzes a number of additional reactions that includethe formation of Fo-P, when the enzyme is incubated with Fo and GDP, GTP, pyrophosphate, ortripolyphosphate, and the hydrolysis of F₄₂₀-0 to Fo. All of these side reactions can be rationalized asoccurring by a common mechanism. CofD has no recognized sequence similarity to any previouslycharacterized enzyme.