The chitin catabolic cascade in the marine bacterium Vibrio furnissii - Molecular cloning, isolation, and characterization of a periplasmic chitodextrinase
The chitin catabolic cascade in the marine bacterium Vibrio furnissii - Molecular cloning, isolation, and characterization of a periplasmic chitodextrinase
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DOI：
10.1074/jbc.271.52.33414
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发表时间：
1996-12-27
影响因子：
4.8
通讯作者：
Roseman, S
中科院分区：
文献类型：
--
作者：
Keyhani, NO;Roseman, S
在Vibrioelastissii中的几丁质酶包括几个信号转导系统和许多蛋白质，其中两种酶是周质的，并将几丁质寡糖转化为GlcNAc和（GlcNAc）（2）。本文描述了这些独特的酶之一，壳聚糖酶，命名为EndoI。从重组大肠杆菌克隆中分离的蛋白质，表现出（通过SDS-聚丙烯酰胺凝胶电泳）两条酶活性的封闭电泳带壳聚糖糊精酶快速切割几丁质寡糖（GlcNAc）（4）至（GlcNAc）（2），和（GlcNAc）从（5.6）到（GlcNAc）（2）和（GlcNAc）（3），EndoI在毫摩尔范围内被底物抑制，并且对含有（GlcNAc）（2）的几丁质、葡糖胺寡糖、糖蛋白和糖肽无活性。这两种蛋白都缺少预测的N-末端31个氨基酸，对应于共有的原核信号肽。因此，大肠杆菌可识别并加工这一信号序列。虽然对几丁质无活性，但EndoI的预测氨基酸序列显示出与许多几丁质酶的相似性，其中8个氨基酸在10个或更多的同源蛋白质中完全保守。然而，EndoI中没有“共有”几丁质结合结构域。
Chitin catabolism in Vibrio furnissii comprises several signal transducing systems and many proteins, Two of these enzymes are periplasmic and convert chitin oligosaccharides to GlcNAc and (GlcNAc)(2), One of these unique enzymes, a chitodextrinase, designated EndoI, is described here.The protein, isolated from a recombinant Escherichia coli clone, exhibited (via SDS-polyacrylamide gel electrophoresis) two enzymatically active, close running bands (similar to mass of 120 kDa) with identical N-terminal sequences, The chitodextrinase rapidly cleaved chitin oligosaccharides, (GlcNAc)(4) to (GlcNAc)(2), and (GlcNAc)(5.6) to (GlcNAc)(2) and (GlcNAc)(3), EndoI was substrate inhibited in the millimolar range and was inactive with chitin, glucosamine oligosaccharides, glycoproteins, and glycopeptides containing (GlcNAc)(2).The sequence of the cloned gene indicates that it encodes a 112,690-kDa protein (1046 amino acids), Both proteins lacked the predicted N-terminal 31 amino acids, corresponding to a consensus prokaryotic signal peptide. Thus, E, coli recognizes and processes this V, furnissii signal sequence, Although inactive with chitin, the predicted amino acid sequence of EndoI displayed similarities to many chitinases, with 8 amino acids completely conserved in 10 or more of the homologous proteins, There was, however, no ''consensus'' chitin-binding domain in EndoI.