The Structural and Biochemical Basis of Apocarotenoid Processing by β-Carotene Oxygenase-2.
The Structural and Biochemical Basis of Apocarotenoid Processing by β-Carotene Oxygenase-2.
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DOI：
10.1021/acschembio.0c00832
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发表时间：
2021-03-19
影响因子：
4
通讯作者：
von Lintig J
中科院分区：
文献类型：
--
作者：
Bandara S;Thomas LD;Ramkumar S;Khadka N;Kiser PD;Golczak M;von Lintig J
在哺乳动物中，类胡萝卜素通过两种类胡萝卜素裂解加氧酶转化为脱辅基类胡萝卜素，包括维生素A。虽然关于β-胡萝卜素加氧酶-1（BCO 1）和维生素A代谢的知识已经大大增加，但β-胡萝卜素加氧酶-2（BCO 2）的功能仍然不太清楚。我们在这里研究了BCO 2在长链β-脱辅基类胡萝卜素代谢中的作用，这是最近出现的哺乳动物生物学中公认的调节分子。我们发现，重组鼠BCO 2通过在C9、C10位氧化裂解将β-脱辅基类胡萝卜素底物的醇、醛和羧酸转化为β-紫罗酮和二脱辅基类胡萝卜素产物。链长的变化（C20至C40）和紫罗酮环的脱辅基类胡萝卜素基板的网站修改并不妨碍催化活性或改变区域选择性的双键裂解的BCO 2。同位素标记实验表明，脱辅基类胡萝卜素的双键断裂遵循双加氧酶反应机制。结构建模和定点诱变确定的氨基酸残基在基板隧道的BCO 2脱辅基类胡萝卜素的结合和催化加工是至关重要的。缺乏BCO 2的小鼠在肝脏中积累了脱辅基类胡萝卜素，表明这种酶参与了脱辅基类胡萝卜素的代谢。总之，我们的研究为BCO 2催化提供了新的结构和功能见解，并将该酶确定为小鼠脱辅基类胡萝卜素稳态的关键组分。
In mammals, carotenoids are converted by two carotenoid cleavage oxygenases into apocarotenoids, including vitamin A. Although knowledge about β-carotene oxygenase-1 (BCO1) and vitamin A metabolism has tremendously increased, the function of β-carotene oxygenase-2 (BCO2) remains less well defined. We here studied the role of BCO2 in the metabolism of long chain β-apocarotenoids, which recently emerged as putative regulatory molecules in mammalian biology. We showed that recombinant murine BCO2 converted the alcohol, aldehyde, and carboxylic acid of a β-apocarotenoid substrate by oxidative cleavage at position C9,C10 into a β-ionone and a diapocarotenoid product. Chain length variation (C20 to C40) and ionone ring site modifications of the apocarotenoid substrate did not impede catalytic activity or altered the regioselectivity of double bond cleavage by BCO2. Isotope labelling experiments revealed that the double bond cleavage of an apocarotenoid followed a dioxygenase reaction mechanism. Structural modeling and site directed mutagenesis identified amino acid residues in the substrate tunnel of BCO2 that are critical for apocarotenoid binding and catalytic processing. Mice deficient for BCO2 accumulated apocarotenoids in their livers, indicating that the enzyme engages in apocarotenoid metabolism. Together, our study provides novel structural and functional insights into BCO2 catalysis and establishes the enzyme as key component of apocarotenoid homeostasis in mice.
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视网膜类似（视觉）周期的化学。
影响因子：
62.1
作者：
Kiser, Philip D.;Golczak, Marcin;Palczewski, Krzysztof
通讯作者：
Palczewski, Krzysztof
影响因子：
4.8
作者：
Eroglu, Abdulkerim;Hruszkewycz, Damian P.;Harrison, Earl H.
通讯作者：
Harrison, Earl H.
影响因子：
4.8
作者：
dela Sena, Carlo;Sun, Jian;Harrison, Earl H.
通讯作者：
Harrison, Earl H.
DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
4.8
作者：
Amengual, Jaume;Widjaja-Adhi, M. Airanthi K.;von Lintig, Johannes
通讯作者：
von Lintig, Johannes