Expression in Escherichia coli and properties of the carotene ketolase from Haematococcus pluvialis
Expression in Escherichia coli and properties of the carotene ketolase from Haematococcus pluvialis
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DOI：
10.1016/0378-1097(96)00187-5
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发表时间：
1996-07-01
影响因子：
2.1
通讯作者：
Sandmann, G
中科院分区：
文献类型：
--
作者：
Breitenbach, J;Misawa, N;Sandmann, G
来自雨红球菌的功能性β -胡萝卜素酮酶基因bkt在产生β -胡萝卜素或玉米黄质的大肠杆菌转化体中得到了高水平的表达，这是由于存在来自Erwinia uredoora的额外类胡萝卜素基因。证明了酮基的插入需要分子氧。从β -胡萝卜素两步酮醇酶反应的最终产物是角黄素（4,4′-二酮- β -胡萝卜素），中间产物是4-单酮衍生物棘烯酮。根据携带Erwinia羟化酶基因crtZ和bkt的大肠杆菌转化虾青素的动力学数据，建立了β -胡萝卜素转化虾青素的反应序列。我们得出结论，除了虾青素外，在转化过程中积累的类胡萝卜素玉米黄质和阿多黄质是副反应的产物，而不是虾青素的直接前体。讨论了酮类衍生物形成的可能机理。
High level expression of the functional beta-carotene ketolase gene bkt from Haematococcus pluvialis occurred in Escherichia coli transformants producing beta-carotene or zeaxanthin as a result of the presence of additional carotenoid genes from Erwinia uredovora. Requirement of molecular oxygen for the insertion of the keto group was demonstrated. The final product of this two-step ketolase reaction from beta-carotene is canthaxanthin (4,4'-diketo-beta-carotene) with the 4-monoketo derivative echinenone as an intermediate. A reaction sequence for the formation of astaxanthin from beta-carotene was established based on kinetic data on astaxanthin formation in E. coli transformants carrying the hydroxylase gene crtZ from Erwinia along with bkt. We conclude that the carotenoids zeaxanthin and adonixanthin which accumulate in addition to astaxanthin in this transformant are products of side reactions rather than direct precursors of astaxanthin. The possible mechanisms for the formation of the keto derivatives are discussed.