Chlorophyllide a oxidoreductase preferentially catalyzes 8‐vinyl reduction over B‐ring reduction of 8‐vinyl chlorophyllide a in late steps of bacteriochlorophyll biosynthesis
Chlorophyllide a oxidoreductase preferentially catalyzes 8‐vinyl reduction over B‐ring reduction of 8‐vinyl chlorophyllide a in late steps of bacteriochlorophyll biosynthesis
复制标题
在细菌叶绿素生物合成的后期步骤中，叶绿素a氧化还原酶优先催化8-乙烯基还原，而不是8-乙烯基叶绿素a的B环还原
DOI：
10.1002/cbic.201900785
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发表时间：
2020
期刊：
影响因子：
3.2
通讯作者：
Fujita Yuichi
中科院分区：
文献类型：
--
作者：
Yamamoto Haruki;Mizoguchi Tadashi;Tsukatani Yusuke;Tamiaki Hitoshi;Kurisu Genji;Fujita Yuichi
细菌叶绿素（Bacteriochlorophylla，BChl）是光合作用的必需色素。在荚膜红细菌BChl生物合成的后期步骤中，8-乙烯基叶绿素a（8 V-Chlide）的C8乙烯基和C7=C8双键分别被C8乙烯基还原酶（8VR）BciA和固氮酶样酶叶绿素a氧化还原酶（COR）还原，以产生3-乙烯基-细菌叶绿素a。 最近，我们在COR中发现了8VR活动。然而，COR 8VR活性的动力学参数仍然未知，而COR C7=C8还原酶活性和BciA的动力学参数已被报道。在这里，我们通过使用8 V‐Chlide确定COR 8VR活性的动力学参数。 8 V-氯化物的Km值为1.4 μM，远低于氯化物C7=C8还原测定的6.2 μM。 COR的双重活性的动力学参数表明，当在BChl生物合成期间提供两种底物时，COR优先催化8 V-Chlide的C8乙烯基的还原而不是C7=C8还原。
Bacteriochlorophylla(BChl) is an essential pigment for anoxygenic photosynthesis. In late steps of the BChl biosynthesis ofRhodobacter capsulatus, the C8 vinyl group and C7=C8 double bond of 8‐vinyl chlorophyllidea(8 V‐Chlide) are reduced by a C8 vinyl reductase (8VR), BciA, and a nitrogenase‐like enzyme, chlorophyllideaoxidoreductase (COR), respectively, to produce 3‐vinyl‐bacteriochlorphyllidea. Recently, we discovered 8VR activity in COR. However, the kinetic parameters of the COR 8VR activity remain unknown, while those of the COR C7=C8 reductase activity and BciA have been reported. Here, we determined the kinetic parameters of COR 8VR activity by using 8 V‐Chlide. TheKmvalue for 8 V‐Chlide was 1.4 μM, which is much lower than the 6.2 μM determined for the C7=C8 reduction of Chlide. The kinetic parameters of the dual activities of COR suggest that COR catalyzes the reduction of the C8 vinyl group of 8 V‐Chlide preferentially over C7=C8 reduction when both substrates are supplied during BChl biosynthesis.