Huang Lanxiang, Shizume Arisa, Nogawa Masahiro, Taguchi Goro, Shimosaka Makoto
Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano, Japan.
Biosci Biotechnol Biochem. 2012;76(3):517-22. doi: 10.1271/bbb.110822.
Chitiniphilus shinanonensis strain SAY3(T) is a chitinolytic bacterium isolated from moat water of Ueda Castle in Nagano Prefecture, Japan. Fifteen genes encoding putative chitinolytic enzymes (chiA-chiO) have been isolated from this bacterium. Five of these constitute a single operon (chiCDEFG). The open reading frames of chiC, chiD, chiE, and chiG show sequence similarity to family 18 chitinases, while chiF encodes a polypeptide with two chitin-binding domains but no catalytic domain. Each of the five genes was successfully expressed in Escherichia coli, and the resulting recombinant proteins were characterized. Four of the recombinant proteins (ChiC, ChiD, ChiE, and ChiG) exhibited endo-type chitinase activity toward chitinous substrates, while ChiF showed no chitinolytic activity. In contrast to most endo-type chitinases, which mainly produce a dimer of N-acetyl-D-glucosamine (GlcNAc) as final product, ChiG completely split the GlcNAc dimer into GlcNAc monomers, indicating that it is a novel chitinase.
信州几丁质嗜纤维菌SAY3(T)菌株是从日本长野县上田城护城河水中分离出的一种几丁质分解细菌。已从该细菌中分离出15个编码假定几丁质分解酶的基因（chiA - chiO）。其中5个基因构成一个单一操纵子（chiCDEFG）。chiC、chiD、chiE和chiG的开放阅读框与18家族几丁质酶具有序列相似性，而chiF编码一种具有两个几丁质结合结构域但无催化结构域的多肽。这5个基因均在大肠杆菌中成功表达，并对产生的重组蛋白进行了表征。4种重组蛋白（ChiC、ChiD、ChiE和ChiG）对几丁质底物表现出内切型几丁质酶活性，而ChiF未表现出几丁质分解活性。与大多数主要产生N - 乙酰 - D - 葡萄糖胺（GlcNAc）二聚体作为最终产物的内切型几丁质酶不同，ChiG可将GlcNAc二聚体完全分解为GlcNAc单体，表明它是一种新型几丁质酶。
