Identification of the Cellobiose 2-Epimerase Gene in the Genome of Bacteroides fragilis NCTC 9343
Identification of the Cellobiose 2-Epimerase Gene in the Genome of Bacteroides fragilis NCTC 9343
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DOI：
10.1271/bbb.80691
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发表时间：
2009-02-01
影响因子：
1.6
通讯作者：
Ito, Susumu
中科院分区：
文献类型：
--
作者：
Senoura, Takeshi;Taguchi, Hidenori;Ito, Susumu
纤维二糖2-差向异构酶（CE，EC 5.1.3.11）催化纤维二糖可逆差向异构化为4-O-β-D-吡喃葡萄糖基-D-甘露糖。在本研究中，我们在非纤维素分解脆弱类杆菌NCTC 9343的基因组序列中发现了一个CE基因。在大肠杆菌细胞中表达的重组酶在还原性末端葡萄糖的C-2位和纤维寡糖、乳糖、β-甘露二糖（4-O-β-D-吡喃甘露糖基-D-甘露糖）和球丙糖[O-α-D-吡喃半乳糖基-（1 -> 4）-O-β-D-吡喃半乳糖基-（1-> 4）-D-葡萄糖]的甘露糖部分催化羟基立体异构。来自B的CE。fragilis与已报道的功能CE的同一性低于40%。它与厚壁菌门、拟杆菌门、变形菌门、绿杆菌门和疣微菌门的细菌基因组序列中功能未知的N-酰基-D-葡糖胺2-差向异构酶样假设蛋白质具有44-63%的同一性。另一方面，它与功能性N-酰基-D-葡糖胺2-差向异构酶的同一性低于26%。基于氨基酸的同源性和系统发育位置的功能差向异构酶，我们强调，许多基因的推定N-酰基-D-葡糖胺2-差向异构酶和相关的假设蛋白质的未知功能的细菌基因组中的日期应注释为CE样蛋白或推定的CE。
Cellobiose 2-epimerase (CE, EC 5.1.3.11) catalyzes the reversible epimerization of cellobiose to 4-O-beta-D-glucopyranosyl-D-mannose. In this study, we found a CE gene in the genome sequence of non-cellulolytic Bacteroides fragilis NCTC 9343. The recombinant enzyme, expressed in Escherichia coli cells, catalyzed a hydroxyl stereoisomerism at the C-2 positions of the reducing terminal glucose and at the mannose moiety of cello-oligosaccharides, lactose, beta-mannobiose (4-O-beta-D-mannopyranosyl-D-mannose), and globotriose [O-alpha-D-galactopyranosyl-(1 -> 4)-O-beta-D-galactopyranosyl-(1 -> 4)-D-glucose]. The CE from B. fragilis showed less than 40% identity to reported functional CEs. It exhibited 44-63% identities to N-acyl-D-glucosamine 2-epimerase-like hypothetical proteins of unknown function in bacteria] genome sequences of the phyla Firmicutes, Bacteroidetes, Proteobacteria, Chloroflexi, and Verrucomicrobia. On the other hand, it showed less than 26% identity to functional N-acyl-D-glucosamine 2-epimerases. Based on the amino acid homology and phylogenetic positions of the functional epimerases, we emphasize that many genes for putative N-acyl-D-glucosamine 2-epimerases and related hypothetical proteins of unknown function reported to date in the bacterial genomes should be annotated as CE-like proteins or putative CEs.