Identification of an L-Arabinose Reductase Gene in Aspergillus niger and Its Role in L-Arabinose Catabolism
Identification of an L-Arabinose Reductase Gene in Aspergillus niger and Its Role in L-Arabinose Catabolism
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DOI：
10.1074/jbc.m110.113399
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发表时间：
2010-07-30
影响因子：
4.8
通讯作者：
Richard, Peter
中科院分区：
文献类型：
--
作者：
Mojzita, Dominik;Penttila, Merja;Richard, Peter
真核微生物中L-阿拉伯糖催化途径中的第一种酶是还原酶，将L-阿拉伯糖还原为L-阿拉伯糖醇。催化这种还原的酶通常是非特异性的，并且也将D-木糖还原为木糖醇，这是真核D-木糖催化的第一步。目前尚不清楚微生物是否根据碳源使用不同的酶。在这里，我们表明，尼日尔利用两种不同的酶。我们确定，克隆和表征的L-阿拉伯糖还原酶，larA，这是从D-木糖还原酶，xyrA不同。larA在L-阿拉伯糖上上调，而xyrA在D-木糖上上调。然而，在D-木糖上也存在larA的初始上调，但在约4小时后逐渐消失。larA基因在A.尼日尔导致在Larabinose上生长缓慢的表型，而在D-木糖上的生长不受影响。L-阿拉伯糖还原酶可将L-阿拉伯糖和D-木糖转化为它们相应的糖醇，但对L-阿拉伯糖具有更高的亲和力。L-阿拉伯糖的Km为54 +/- 6 mM，D-木糖的Km为155 +/- 15 mM。
The first enzyme in the pathway for L-arabinose catabolism in eukaryotic microorganisms is a reductase, reducing L-arabinose to L-arabitol. The enzymes catalyzing this reduction are in general nonspecific and would also reduce D-xylose to xylitol, the first step in eukaryotic D-xylose catabolism. It is not clear whether microorganisms use different enzymes depending on the carbon source. Here we show that Aspergillus niger makes use of two different enzymes. We identified, cloned, and characterized an L-arabinose reductase, larA, that is different from the D-xylose reductase, xyrA. The larA is up-regulated on L-arabinose, while the xyrA is up-regulated on D-xylose. There is however an initial up-regulation of larA also on D-xylose but that fades away after about 4 h. The deletion of the larA gene in A. niger results in a slow growth phenotype on Larabinose, whereas the growth on D-xylose is unaffected. The L-arabinose reductase can convert L-arabinose and D-xylose to their corresponding sugar alcohols but has a higher affinity for L-arabinose. The K-m for L-arabinose is 54 +/- 6 mM and for D-xylose 155 +/- 15 mM.