The crystal structure of an<scp>lll</scp>-configured depsipeptide substrate analogue bound to isopenicillin N synthase
作者:Wei Ge、Ian J. Clifton、Jeanette E. Stok、Robert M. Adlington、Jack E. Baldwin、Peter J. Rutledge
DOI:10.1039/b910170e
日期:——
Isopenicillin N synthase (IPNS) is a non-heme iron(II) oxidase, which catalyses the biosynthesis of isopenicillin N (IPN) from the tripeptide δ-L-α-aminoadipoyl-L-cysteinyl-D-valine (LLD-ACV) in a remarkable oxidative bicyclisation reaction. The natural substrate for IPNS is the LLD-configured tripeptide. LLL-ACV is not turned over by the enzyme, but inhibits turnover of the LLD-tripeptide. The mechanism by which this inhibition takes place is not fully understood. Recent studies have employed a range of LLD-configured depsipeptide substrate analogues in crystallographic studies to probe events preceding β-lactam closure in the IPNS reaction cycle. Herein, we report the first crystal structure of IPNS in complex with an LLL-configured depsipeptide analogue, δ-L-α-aminoadipoyl-L-cysteine (1-(R)-carboxy-2-thiomethyl)ethyl ester (LLL-ACOmC). This report describes the crystal structure of the IPNS:Fe(II):LLL-ACOmC complex to 2.0 Å resolution, and discusses attempts to oxygenate this complex at high pressure in order to probe the mechanism by which LLL-configured substrates inhibit IPNS catalysis.
异青霉素 N 合酶 (IPNS) 是一种非血红素铁 (II) 氧化酶,可催化三肽 δ-L-α-氨基己二酰-L-半胱氨酰-D-缬氨酸 (LLD-ACV) 生物合成异青霉素 N (IPN)发生显着的氧化双环化反应。 IPNS 的天然底物是 LLD 配置的三肽。 LLL-ACV 不会被酶转化,但会抑制 LLD-三肽的转化。这种抑制发生的机制尚不完全清楚。最近的研究在晶体学研究中采用了一系列 LLD 配置的缩酚肽底物类似物来探测 IPNS 反应循环中 β-内酰胺闭合之前的事件。在此,我们报道了IPNS与LLL配置的缩酚肽类似物δ-L-α-氨基己二酰-L-半胱氨酸(1-(R)-羧基-2-硫甲基)乙酯(LLL-ACOmC)复合物的第一个晶体结构)。该报告以 2.0 Å 分辨率描述了 IPNS:Fe(II):LLL-ACOmC 复合物的晶体结构,并讨论了在高压下对该复合物进行氧化的尝试,以探讨 LLL 配置底物抑制 IPNS 催化的机制。
Isopenicillin N Synthase Mediates Thiolate Oxidation to Sulfenate in a Depsipeptide Substrate Analogue: Implications for Oxygen Binding and a Link to Nitrile Hydratase?
作者:Wei Ge、Ian J. Clifton、Jeanette E. Stok、Robert M. Adlington、Jack E. Baldwin、Peter J. Rutledge
DOI:10.1021/ja8005397
日期:2008.8.1
IsopenicillinNsynthase (IPNS) is a nonheme iron oxidase that catalyzes the central step in the biosynthesis of beta-lactam antibiotics: oxidative cyclization of the linear tripeptide delta-L-alpha-aminoadipoyl-L-cysteinyl-D-valine (ACV) to isopenicillinN (IPN). The ACV analogue delta-L-alpha-aminoadipoyl-L-cysteine (1-(S)-carboxy-2-thiomethyl)ethyl ester (ACOmC) has been synthesized as a mechanistic
异青霉素 N 合酶 (IPNS) 是一种非血红素铁氧化酶,可催化 β-内酰胺抗生素生物合成的核心步骤:线性三肽 delta-L-α-氨基己二酰-L-半胱氨酰-D-缬氨酸 (ACV) 的氧化环化异青霉素 N (IPN)。ACV 类似物 delta-L-α-氨基己二酰-L-半胱氨酸(1-(S)-羧基-2-硫甲基)乙酯(ACOmC)已合成为 IPNS 催化的机械探针,并用酶结晶。厌氧 IPNS/Fe(II)/ACOmC 复合物的晶体结构确定为 1.80 A 分辨率,揭示了高度拥挤的活性位点区域。通过将这些厌氧生长的晶体暴露在高压氧气中,观察到了意想不到的次磺酸盐产物,在 IPNS 活性位点内与铁络合。提出了形成次磺酸盐-铁络合物的机制,并且似乎 ACOmC 在其与 IPNS 反应的最早阶段遵循不同的反应途径。因此,似乎氧(共底物)在与之前 IPNS 研究中观察到的不同的位点结合,在此过程中从铁中置换了水配体。以前在