Jannatipour M, Soto-Gil R W, Childers L C, Zyskind J W
J Bacteriol. 1987 Aug;169(8):3785-91. doi: 10.1128/jb.169.8.3785-3791.1987.
The gene encoding N,N'-diacetylchitobiase (chitobiase) of the chitinolytic marine bacterium Vibrio harveyi has been isolated. While expression of the chitobiase gene (chb) was inducible by N,N'-diacetylchitobiose in V. harveyi, it was expressed constitutively when cloned in Escherichia coli, suggesting that controlling elements are not closely linked to chb. Chitobiase was found in the membrane fraction of E. coli cells containing plasmids with the cloned V. harveyi chb gene. When membranes of such cells were separated on Osborn gradients, chitobiase activity was found mainly in the outer membrane band. Translocation of the enzyme to the outer membrane was accompanied by cleavage of a signal peptide. A fusion protein, in which 22 amino acids from the amino terminus of prechitobiase were replaced with 21 amino acids from the pUC19 lacZ amino terminus, was not processed, and 99% of the activity was located in the cytoplasmic fraction. A homology to six amino acids surrounding the lipoprotein processing and modification site was found near the amino terminus of prechitobiase.
已分离出几丁质分解海洋细菌哈维氏弧菌编码N，N'-二乙酰壳二糖酶（壳二糖酶）的基因。虽然壳二糖酶基因（chb）在哈维氏弧菌中可被N，N'-二乙酰壳二糖诱导表达，但当克隆到大肠杆菌中时它组成型表达，这表明调控元件与chb没有紧密连锁。在含有克隆了哈维氏弧菌chb基因的质粒的大肠杆菌细胞的膜部分中发现了壳二糖酶。当此类细胞的膜在奥斯本梯度上分离时，壳二糖酶活性主要存在于外膜带中。该酶转运至外膜伴随着信号肽的切割。一种融合蛋白，其中前壳二糖酶氨基末端的22个氨基酸被pUC19 lacZ氨基末端的21个氨基酸取代，未被加工，99%的活性位于细胞质部分。在前壳二糖酶氨基末端附近发现了与脂蛋白加工和修饰位点周围六个氨基酸的同源性。
