VTT Technical Research Centre of Finland, Espoo, Finland.
FEBS Lett. 2010 Aug 20;584(16):3540-4. doi: 10.1016/j.febslet.2010.06.037. Epub 2010 Jul 21.
L-Xylulose reductase is part of the eukaryotic pathway for l-arabinose catabolism. A previously identified L-xylulose reductase in Hypocrea jecorina turned out to be not the 'true' one since it was not upregulated during growth on L-arabinose and the deletion strain showed no reduced L-xylulose reductase activity but instead lost the D-mannitol dehydrogenase activity. In this communication we identified the 'TRUE'L-xylulose reductase in Aspergillus niger. The gene, lxrA (JGI177736), is upregulated on L-arabinose and the deletion results in a strain lacking the NADPH-specific L-xylulose reductase activity and having reduced growth on l-arabinose. The purified enzyme had a K(m) for L-xylulose of 25 mM and a nu(max) of 650 U/mg.
木酮糖还原酶是真核生物 L-阿拉伯糖分解代谢途径的一部分。先前在 Hypocrea jecorina 中鉴定出的 L-木酮糖还原酶并不是“真正的”酶，因为它在 L-阿拉伯糖生长过程中没有上调，缺失菌株没有降低的 L-木酮糖还原酶活性，而是失去了 D-甘露醇脱氢酶活性。在本通讯中，我们鉴定了黑曲霉中的“真正的”L-木酮糖还原酶。该基因 lxrA（JGI177736）在 L-阿拉伯糖上上调，缺失导致菌株缺乏 NADPH 特异性 L-木酮糖还原酶活性，并在 L-阿拉伯糖上生长减少。纯化的酶对 L-木酮糖的 K(m)为 25 mM，nu(max)为 650 U/mg。
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