Metabolism of sucrose and its five isomers by Fusobacterium mortiferum
Metabolism of sucrose and its five isomers by Fusobacterium mortiferum
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DOI：
10.1099/00221287-148-3-843
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发表时间：
2002-03-01
期刊：
影响因子：
2.8
通讯作者：
Thompson, J
中科院分区：
文献类型：
--
作者：
Pikis, A;Immel, S;Thompson, J
死亡梭杆菌利用蔗糖[α（1->2）键中的葡萄糖-果糖]及其五种异构体α-D-葡萄糖基-D-果糖作为生长的能源。蔗糖生长的细胞被蔗糖-6-磷酸水解酶（S6 PH）和果糖激酶（FK）诱导，但这两种酶在异构化合物上生长期间不表达高于组成水平。先前在蔗糖异构体海藻酮糖α（1->1）、松二糖α（1->3）、麦芽酮糖α（1->4）、明串珠菌二糖α（1->5）和帕拉金糖α（1->6）上生长的细胞的提取物含有高水平的NAD（+）加上金属依赖性磷酸-α-葡糖苷酶（MalH）。后一种酶在蔗糖生长过程中没有诱导。MalH催化五种异构体的6 '-磷酸化衍生物水解，产生葡萄糖6-磷酸和果糖，但蔗糖6-磷酸本身不是底物。出乎意料的是，MalH水解了显色类似物对硝基苯基葡萄糖苷6-磷酸的α-和β-连接立体异构体。基因malH与malB和malR相邻，malB和malR分别编码磷酸烯醇化酸依赖性糖：磷酸转移酶系统的Ell（CB）组分和推定的调节蛋白。作者认为，F.在mortiferum中，malB和malH的产物催化蔗糖的五种异构体和相关的α-连接的葡糖苷的磷酸化易位和细胞内水解。与malB和malH同源的基因存在于肺炎克雷伯菌和肠出血性大肠杆菌O 157：H7菌株中。这两种菌在蔗糖上生长良好，但只有K. pneumoniae在异构体化合物上表现出生长。
Fusobacterium mortiferum utilizes sucrose [glucose-fructose in alpha(1-->2) linkage] and its five isomeric alpha-D-glucosyl-D-fructoses as energy sources for growth. Sucrose-grown cells are induced for both sucrose-6-phosphate hydrolase (S6PH) and fructokinase (FK), but the two enzymes are not expressed above constitutive levels during growth on the isomeric compounds. Extracts of cells grown previously on the sucrose isomers trehalulose alpha(1-->1), turanose alpha(1-->3), maltulose alpha(1-->4), leucrose alpha(1-->5) and palatinose alpha(1-->6) contained high levels of an NAD(+) plus metal-dependent phospho-alpha-glucosidase (MalH). The latter enzyme was not induced during growth on sucrose. MalH catalysed the hydrolysis of the 6'-phosphorylated derivatives of the five isomers to yield glucose 6-phosphate and fructose, but sucrose 6-phosphate itself was not a substrate. Unexpectedly, MalH hydrolysed both alpha- and beta-linked stereomers of the chromogenic analogue p-nitrophenyl glucoside 6-phosphate. The gene malH is adjacent to malB and malR, which encode an Ell(CB) component of the phosphoenolpyruvate-dependent sugar: phosphotransferase system and a putative regulatory protein, respectively. The authors suggest that for F. mortiferum, the products of malB and malH catalyse the phosphorylative translocation and intracellular hydrolysis of the five isomers of sucrose and of related alpha-linked glucosides. Genes homologous to malB and malH are present in both Klebsiella pneumoniae and the enterohaemorrhagic strain Escherichia coli O157:H7. Both these organisms grew well on sucrose, but only K. pneumoniae exhibited growth on the isomeric compounds.