Selig M, Xavier K B, Santos H, Schönheit P
Institut für Pflanzenphysiologie und Mikrobiologie, Fachbereich Biologie, Freie Universität Berlin, Königin-Luise-Strasse 12-16a, D-14195 Berlin, Germany.
Arch Microbiol. 1997 Apr;167(4):217-32. doi: 10.1007/BF03356097.
The Embden-Meyerhof (EM) or Entner-Doudoroff (ED) pathways of sugar degradation were analyzed in representative species of the hyperthermophilic archaeal genera Thermococcus, Desulfurococcus, Thermoproteus, and Sulfolobus, and in the hyperthermophilic (eu)bacterial genus Thermotoga. The analyses included (1) determination of 13C-labeling patterns by 1H- and 13C-NMR spectroscopy of fermentation products derived from pyruvate after fermentation of specifically 13C-labeled glucose by cell suspensions, (2) identification of intermediates of sugar degradation after conversion of 14C-labeled glucose by cell extracts, and (3) measurements of enzyme activities in cell extracts. Thermococcus celer and Thermococcus litoralis fermented 13C-glucose to acetate and alanine via a modified EM pathway (100%). This modification involves ADP-dependent hexokinase, 6-phosphofructokinase, and glyceraldehyde-3-phosphate:ferredoxin oxidoreductase (GAP:FdOR). Desulfurococcus amylolyticus fermented 13C-glucose to acetate via a modified EM pathway in which GAP:FdOR replaces GAP-DH/phosphoglycerate kinase. Thermoproteus tenax fermented 13C-glucose to low amounts of acetate and alanine via simultaneous operation of the EM pathway (85%) and the ED pathway (15%). Aerobic Sulfolobus acidocaldarius fermented 13C-labeled glucose to low amounts of acetate and alanine exclusively via the ED pathway. The anaerobic (eu)bacterium Thermotoga maritima fermented 13C-glucose to acetate and lactate via the EM pathway (85%) and the ED pathway (15%). Cell extracts contained glucose-6-phosphate dehydrogenase and 2-keto-3-deoxy-6-phosphogluconate aldolase, key enzymes of the conventional phosphorylated ED pathway, and, as reported previously, all enzymes of the conventional EM pathway. In conclusion, glucose was degraded by hyperthermophilic archaea to pyruvate either via modified EM pathways with different types of hexose kinases and GAP-oxidizing enzymes, by the nonphosphorylated ED pathway, or by a combination of both pathways. In contrast, glucose catabolism in the hyperthermophilic (eu)bacterium Thermotoga involves the conventional forms of the EM and ED pathways. The data are in accordance with various previous reports.
在嗜热古菌属嗜热栖热菌、脱硫球菌属、嗜热栖热菌属和硫化叶菌属的代表性物种以及嗜热（真）细菌嗜热栖热袍菌属中，分析了糖降解的Embden-Meyerhof（EM）或Entner-Doudoroff（ED）途径。分析内容包括：（1）通过1H和13C-NMR光谱法测定细胞悬液发酵经特定13C标记的葡萄糖后，丙酮酸发酵产物的13C标记模式；（2）鉴定细胞提取物将14C标记的葡萄糖转化后糖降解的中间产物；（3）测量细胞提取物中的酶活性。嗜热栖热球菌和嗜热栖热海岸球菌通过一种改良的EM途径（100%）将13C-葡萄糖发酵为乙酸盐和丙氨酸。这种改良涉及ADP依赖性己糖激酶、6-磷酸果糖激酶和甘油醛-3-磷酸：铁氧化还原蛋白氧化还原酶（GAP:FdOR）。解淀粉脱硫球菌通过一种改良的EM途径将13C-葡萄糖发酵为乙酸盐，其中GAP:FdOR取代了GAP-DH/磷酸甘油酸激酶。嗜热栖热菌通过EM途径（85%）和ED途径（15%）同时运作，将13C-葡萄糖发酵为少量乙酸盐和丙氨酸。需氧的嗜酸硫化叶菌仅通过ED途径将13C标记的葡萄糖发酵为少量乙酸盐和丙氨酸。厌氧（真）细菌嗜热栖热袍菌通过EM途径（85%）和ED途径（15%）将13C-葡萄糖发酵为乙酸盐和乳酸盐。细胞提取物含有葡萄糖-6-磷酸脱氢酶和2-酮-3-脱氧-6-磷酸葡萄糖酸醛缩酶，这是传统磷酸化ED途径的关键酶，并且如先前报道的那样，还含有传统EM途径的所有酶。总之，嗜热古菌通过不同类型己糖激酶和GAP氧化酶的改良EM途径、非磷酸化ED途径或两种途径的组合，将葡萄糖降解为丙酮酸。相比之下，嗜热（真）细菌嗜热栖热袍菌中的葡萄糖分解代谢涉及传统形式的EM和ED途径。这些数据与先前的各种报道一致。
