The alcohol dehydrogenase system in the xylose-fermenting yeast Candida maltosa.
The alcohol dehydrogenase system in the xylose-fermenting yeast Candida maltosa.
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DOI：
10.1371/journal.pone.0011752
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发表时间：
2010-07-23
期刊：
影响因子：
3.7
通讯作者：
Jiang N
中科院分区：
文献类型：
--
作者：
Lin Y;He P;Wang Q;Lu D;Li Z;Wu C;Jiang N
乙醇脱氢酶（ADH）系统在糖代谢中起着关键作用，不仅涉及乙醇的形成和消耗，而且还涉及一般的“辅因子平衡”机制。麦芽糖假丝酵母能够发酵葡萄糖以及木糖以产生大量的乙醇。本文报道了C.麦芽糖由三个微生物I族ADH基因（CmADH 1、CmADH 2A和CmADH 2B）组成，主要集中在其代谢调节和生理功能上。遗传分析表明，CmADH 2A和CmADH 2B串联定位在染色体上可能是由串联基因重复引起的。体外酶学性质的表征表明，所有三个CmADH具有广泛的底物特异性。同源和异源四聚体的CmADH 1和CmADH 2A的酶谱分析表明，其表达谱和生理功能的碳源和生长阶段是不同的。对ADH 2A缺陷突变株的发酵研究表明，由于CmADH 2A缺陷导致甘油的大量积累，因此CmADH 2A与木糖代谢过程中NAD的再生直接相关。我们的研究结果表明，CmADH 1是负责在葡萄糖代谢过程中乙醇的形成，而CmADH 2A是葡萄糖抑制和功能的积累乙醇转化为乙醛。据我们所知，这是第一次证明ADH基因的功能分离和葡萄糖阻遏的木糖发酵酵母。另一方面，CmADH 1和CmADH 2A都参与了乙醇的形成与NAD再生，以维持有利于从木糖生产木糖醇的NADH/NAD比。而CmADH 2B基因的表达量明显低于其他两个基因，其功能有待进一步证实。
The alcohol dehydrogenase (ADH) system plays a critical role in sugar metabolism involving in not only ethanol formation and consumption but also the general “cofactor balance” mechanism. Candida maltosa is able to ferment glucose as well as xylose to produce a significant amount of ethanol. Here we report the ADH system in C. maltosa composed of three microbial group I ADH genes (CmADH1, CmADH2A and CmADH2B), mainly focusing on its metabolic regulation and physiological function. Genetic analysis indicated that CmADH2A and CmADH2B tandemly located on the chromosome could be derived from tandem gene duplication. In vitro characterization of enzymatic properties revealed that all the three CmADHs had broad substrate specificities. Homo- and heterotetramers of CmADH1 and CmADH2A were demonstrated by zymogram analysis, and their expression profiles and physiological functions were different with respect to carbon sources and growth phases. Fermentation studies of ADH2A-deficient mutant showed that CmADH2A was directly related to NAD regeneration during xylose metabolism since CmADH2A deficiency resulted in a significant accumulation of glycerol. Our results revealed that CmADH1 was responsible for ethanol formation during glucose metabolism, whereas CmADH2A was glucose-repressed and functioned to convert the accumulated ethanol to acetaldehyde. To our knowledge, this is the first demonstration of function separation and glucose repression of ADH genes in xylose-fermenting yeasts. On the other hand, CmADH1 and CmADH2A were both involved in ethanol formation with NAD regeneration to maintain NADH/NAD ratio in favor of producing xylitol from xylose. In contrast, CmADH2B was expressed at a much lower level than the other two CmADH genes, and its function is to be further confirmed.
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影响因子：
5
作者：
BRUINENBERG, PM;DEBOT, PHM;SCHEFFERS, WA
通讯作者：
SCHEFFERS, WA
影响因子：
5.6
作者：
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通讯作者：
YOUNG, ET
DOI：
10.1016/0165-1218(75)90093-2
发表时间：
1975-01-01
期刊：
MUTATION RESEARCH
影响因子：
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作者：
CIRIACY, M
通讯作者：
CIRIACY, M
影响因子：
4
作者：
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通讯作者：
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影响因子：
3.9
作者：
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通讯作者：
Bozzi, A