L-Arabinose degradation pathway in the haloarchaeon Haloferax volcanii involves a novel type of L-arabinose dehydrogenase
L-Arabinose degradation pathway in the haloarchaeon Haloferax volcanii involves a novel type of L-arabinose dehydrogenase
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DOI：
10.1007/s00792-013-0572-2
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发表时间：
2013-11-01
期刊：
影响因子：
2.9
通讯作者：
Schoenheit, Peter
中科院分区：
文献类型：
--
作者：
Johnsen, Ulrike;Sutter, Jan-Moritz;Schoenheit, Peter
研究了L-阿拉伯糖在盐生考古菌中的降解途径。结果表明，L-阿拉伯糖被氧化降解为α-酮戊二酸。在L-阿拉伯糖上生长的过程中，产生了L-阿拉伯糖脱氢酶(L-阿拉伯脱氢酶)。该酶被纯化为130kDa的同源四聚体蛋白，能同时催化N-甲基-D-天冬氨酸和N-甲基-D-天冬氨酸氧化L-阿拉伯糖。编码L-阿拉伯脱氢酶的基因被鉴定为H2O_B0032，重组L-阿拉伯脱氢酶具有与天然酶相似的性质。L-阿拉伯糖缺失突变体不能生长在L阿拉伯糖上，而在葡萄糖和d-木糖上生长不受影响，表明L阿拉伯糖的降解具有特异性。系统发育分析表明，第一个古生菌的L-阿拉伯脱氢酶属于扩展短链脱氢酶/还原酶家族，属于一个新的簇，因此不同于已知的古生菌和细菌的戊糖脱氢酶。此外，火山杆菌细胞提取物还催化了依赖于NADP(+)的L-阿拉伯酸转化为α-酮戊二酸。通过对转录本和缺失突变体的分析，确定了参与这一转化的基因，如最近报道的参与d-木酸转化为α-酮戊二酸的HVO_B0038A、HVO_B0027和HVO_B0039(Johnsen等人。2009年)。
The pathway of l-arabinose degradation was studied in the haloarchaeon Haloferax volcanii. It is shown that l-arabinose is oxidatively degraded to alpha-ketoglutarate. During growth on l-arabinose, l-arabinose dehydrogenase (l-AraDH) was induced. The enzyme was purified as a 130 kDa homotetrameric protein catalyzing the oxidation of l-arabinose with both NADP(+) and NAD(+). The gene encoding l-AraDH was identified as HVO_B0032 and recombinant l-AraDH showed similar properties as the native enzyme. The l-AraDH deletion mutant did not grow on l-arabinose, but grew unaffected on glucose and d-xylose, indicating a specific involvement in l-arabinose degradation. Phylogenetic analyses attribute the first archaeal l-AraDH to the extended short-chain dehydrogenase/reductase (SDRe) family, where it is part of a novel cluster and thus differs from known archaeal and bacterial pentose dehydrogenases. Further, cell extracts of H. volcanii catalyzed the NADP(+)-dependent conversion of l-arabinoate to alpha-ketoglutarate. The genes involved in that conversion were identified by analyses of transcripts and deletion mutants as HVO_B0038A, HVO_B0027 and HVO_B0039 recently reported to be involved in d-xylonate conversion to alpha-ketoglutarate in H. volcanii (Johnsen et al. 2009).