Fructose Degradation in the Haloarchaeon Haloferax volcanii Involves a Bacterial Type Phosphoenolpyruvate-Dependent Phosphotransferase System, Fructose-1-Phosphate Kinase, and Class II Fructose-1,6-Bisphosphate Aldolase
Fructose Degradation in the Haloarchaeon Haloferax volcanii Involves a Bacterial Type Phosphoenolpyruvate-Dependent Phosphotransferase System, Fructose-1-Phosphate Kinase, and Class II Fructose-1,6-Bisphosphate Aldolase
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Haloarchaeon Haloferax volcanii 中的果糖降解涉及细菌型磷酸烯醇丙酮酸依赖性磷酸转移酶系统、1-磷酸果糖激酶和 II 类 1,6-二磷酸果糖醛缩酶
DOI：
10.1128/jb.00200-12
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发表时间：
2012
影响因子：
3.2
通讯作者：
Schönheit
中科院分区：
文献类型：
--
作者：
Johnsen;Schönheit
嗜盐古菌Haloferax volcanii利用果糖作为唯一的碳源和能源。通过转录分析、缺失突变体实验和酶特性鉴定了参与果糖摄取和降解的基因和酶。在果糖上生长期间，编码五种细菌磷酸转移酶系统（PTS）组分酶IIB（EIIB）、酶I（EI）、组氨酸蛋白（HPr）、EIIA和EIIC的同源物的基因簇HVO_1495至HVO_1499作为共转录物被高度上调。HVO_1499的读框内缺失，命名为ptfC（ptf代表果糖磷酸转移酶系统），编码假定的果糖特异性膜组分EIIC，导致果糖上的生长损失，这可以通过反式互补来恢复。HVO_1500（pfkB）和HVO_1494（fba）的转录物，分别编码假定的果糖-1-磷酸激酶（1-PFK）和果糖-1，6-二磷酸醛缩酶（FBA），以及1-PFK和FBA活性在果糖生长的细胞中特异性上调。pfkBandfba敲除突变体在果糖上不生长，而在葡萄糖上的生长不受抑制，表明两种酶在果糖催化剂中的功能参与。同源过表达后获得的重组1-PFK和FBA的特征在于具有指示功能性1-PFK和II类FBA的动力学性质。从这些数据中，我们得出结论，果糖吸收在H。volcanii涉及产生果糖-1-磷酸的果糖特异性PTS，其通过1-PFK和FBA经由果糖-1，6-二磷酸进一步转化为磷酸丙糖。这是第一次报告的功能参与的细菌样PTS和II类FBA的糖代谢的古细菌。
The halophilic archaeon Haloferax volcanii utilizes fructose as a sole carbon and energy source. Genes and enzymes involved in fructose uptake and degradation were identified by transcriptional analyses, deletion mutant experiments, and enzyme characterization. During growth on fructose, the gene cluster HVO_1495 to HVO_1499, encoding homologs of the five bacterial phosphotransferase system (PTS) components enzyme IIB (EIIB), enzyme I (EI), histidine protein (HPr), EIIA, and EIIC, was highly upregulated as a cotranscript. The in-frame deletion of HVO_1499, designatedptfC(ptfstands forphosphotransferase system forfructose) and encoding the putative fructose-specific membrane component EIIC, resulted in a loss of growth on fructose, which could be recovered by complementation intrans. Transcripts of HVO_1500 (pfkB) and HVO_1494 (fba), encoding putative fructose-1-phosphate kinase (1-PFK) and fructose-1,6-bisphosphate aldolase (FBA), respectively, as well as 1-PFK and FBA activities were specifically upregulated in fructose-grown cells.pfkBandfbaknockout mutants did not grow on fructose, whereas growth on glucose was not inhibited, indicating the functional involvement of both enzymes in fructose catabolism. Recombinant 1-PFK and FBA obtained after homologous overexpression were characterized as having kinetic properties indicative of functional 1-PFK and a class II type FBA. From these data, we conclude that fructose uptake in H. volcanii involves a fructose-specific PTS generating fructose-1-phosphate, which is further converted via fructose-1,6-bisphosphate to triose phosphates by 1-PFK and FBA. This is the first report of the functional involvement of a bacterial-like PTS and of class II FBA in the sugar metabolism of archaea.