Wang Yongting, Li Xianghui, Jones Limei H, Pearson Arwen R, Wilmot Carrie M, Davidson Victor L
Department of Biochemistry, The University of Mississippi Medical Center, Jackson, MS 39216, USA.
J Am Chem Soc. 2005 Jun 15;127(23):8258-9. doi: 10.1021/ja051734k.
Tryptophan tryptophylquinone (TTQ) is the prosthetic group of methylamine dehydrogenase (MADH) and is synthesized through post-translational modification of two endogenous tryptophan residues. This modification involves two oxygenation reactions and one cross-linking reaction. It is clearly shown that the incorporation of the second oxygen into betaTrp57 and the covalent cross-linking of betaTrp57 to betaTrp108 are MauG-dependent processes. These reaction steps are severely compromised in vivo when mauG is mutated or deleted. These steps may then be catalyzed in vitro upon addition of MauG to the isolated biosynthetic intermediates. These results also show that TTQ formation is linked to proper assembly of subunits during MADH biosynthesis. Last, these results demonstrate a novel function for the c-type heme protein, MauG, which is consistent with its atypical physical properties. These results are the first description of an enzyme-mediated biosynthesis of a protein-derived cofactor in vitro.
色氨酸 - 色氨酰醌（TTQ）是甲胺脱氢酶（MADH）的辅基，通过两个内源性色氨酸残基的翻译后修饰合成。这种修饰涉及两个氧化反应和一个交联反应。清楚地表明，将第二个氧掺入βTrp57以及βTrp57与βTrp108的共价交联是依赖MauG的过程。当mauG发生突变或缺失时，这些反应步骤在体内会严重受损。然后在体外将MauG添加到分离的生物合成中间体上时，这些步骤可能会被催化。这些结果还表明，TTQ的形成与MADH生物合成过程中亚基的正确组装有关。最后，这些结果证明了c型血红素蛋白MauG的一种新功能，这与其非典型的物理性质一致。这些结果是首次对体外酶介导的蛋白质衍生辅因子生物合成的描述。
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