Structure and Catalytic Mechanism of Yeast 4-Amino-4-deoxychorismate Lyase*
Structure and Catalytic Mechanism of Yeast 4-Amino-4-deoxychorismate Lyase*
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DOI：
10.1074/jbc.m113.480335
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发表时间：
2013-07
期刊：
影响因子：
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通讯作者：
Yaohua Dai;C. Chi;K. Zhou;Wang Cheng;Yong-Liang Jiang;Yan-Min Ren;K. Ruan;Yuxing Chen;Cong-Zhao Zhou
中科院分区：
文献类型：
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作者：
Yaohua Dai;C. Chi;K. Zhou;Wang Cheng;Yong-Liang Jiang;Yan-Min Ren;K. Ruan;Yuxing Chen;Cong-Zhao Zhou
背景：酿酒酵母 Abz2 是一种吡哆醛 5'-磷酸依赖性裂合酶，可将 4-氨基-4-脱氧分支酸转化为对氨基苯甲酸和丙酮酸。结果：Abz2 的晶体结构揭示了两个基本残基：Arg-182 和 Arg-255，这两个残基对于底物结合和/或催化至关重要。结论：Abz2 主导一类独特的单体 ADC 裂解酶。意义：首次对真核生物 ADC 裂解酶的催化结构进行了深入了解。酿酒酵母 Abz2 是一种吡哆醛 5'-磷酸 (PLP) 依赖性裂合酶，可将 4-氨基-4-脱氧分支酸 (ADC) 转化为对氨基苯甲酸和丙酮酸。为了研究催化机制，我们确定了与 PLP 复合的 Abz2 的 1.9 Å 分辨率晶体结构，代表了第一个真核 ADC 裂解酶结构。与大肠杆菌 ADC 裂解酶（其二聚化对于活性位点的形成至关重要）不同，Abz2 的整体结构显示为两个结构域的单体。在域间裂口处，辅因子 PLP 分子与残基 Lys-251 形成席夫碱。计算模拟定义了一个基本夹具，用于将底物 ADC 定向为适当的姿势，并通过定点诱变结合酶活性测定进行了验证。总之，我们提出了由酵母 Abz2 主导的一类独特单体 ADC 裂合酶的假定催化机制。
Background: Saccharomyces cerevisiae Abz2 is a pyridoxal 5′-phosphate-dependent lyase that converts 4-amino-4-deoxychorismate to para-aminobenzoate and pyruvate. Results: Crystal structure of Abz2 reveals two basic residues, Arg-182 and Arg-255, crucial for the substrate binding and/or catalysis. Conclusion: Abz2 leads a unique class of monomeric ADC lyases. Significance: Provided is the first structural insight into the catalysis of a eukaryotic ADC lyase. Saccharomyces cerevisiae Abz2 is a pyridoxal 5′-phosphate (PLP)-dependent lyase that converts 4-amino-4-deoxychorismate (ADC) to para-aminobenzoate and pyruvate. To investigate the catalytic mechanism, we determined the 1.9 Å resolution crystal structure of Abz2 complexed with PLP, representing the first eukaryotic ADC lyase structure. Unlike Escherichia coli ADC lyase, whose dimerization is critical to the formation of the active site, the overall structure of Abz2 displays as a monomer of two domains. At the interdomain cleft, a molecule of cofactor PLP forms a Schiff base with residue Lys-251. Computational simulations defined a basic clamp to orientate the substrate ADC in a proper pose, which was validated by site-directed mutageneses combined with enzymatic activity assays. Altogether, we propose a putative catalytic mechanism of a unique class of monomeric ADC lyases led by yeast Abz2.