Vionis A P, Niemeyer F, Karagouni A D, Schrempf H
Universität Osnabrück, Germany.
Appl Environ Microbiol. 1996 May;62(5):1774-80. doi: 10.1128/aem.62.5.1774-1780.1996.
Streptomyces lividans (pCHIO12), which carries the previously cloned Streptomyces olivaceoviridis exo-chiO1 gene on a multicopy vector, secretes a 59-kDa exochitinase, consisting of a catalytic domain (40 kDa), a central fibronectin type III-like module, and a chitin-binding domain (12 kDa). The propagation rate of S. lividans (pCHIO12) was higher in soil microcosms amended with fungal mycelia than in those containing crab chitin. Comparative biochemical and immunological studies allowed the following conclusions to be drawn. Within soil microcosm systems amended with crab shell chitin or chitin-containing Aspergillus proliferans mycelia, the strain expressed the clones exo-chiO1 gene and produced high quantities of a 59-kDa exochitinase. The enzyme was preferentially attached via its binding domain to the pellet from soil or liquid cultures. In contrast, truncated forms of 47, 40, and 25 kDa could be easily extracted from soil. The relative proportions of the 59-kDa enzyme and its truncated forms varied depending on the source of chitin and differed in soil and in liquid cultures.
淡青链霉菌（pCHIO12）在多拷贝载体上携带先前克隆的橄榄绿链霉菌外切几丁质酶O1基因，可分泌一种59 kDa的外切几丁质酶，该酶由一个催化结构域（40 kDa）、一个中央纤连蛋白III型样模块和一个几丁质结合结构域（12 kDa）组成。在添加了真菌菌丝体的土壤微宇宙中，淡青链霉菌（pCHIO12）的繁殖速率高于含有蟹壳几丁质的土壤微宇宙。通过比较生化和免疫学研究得出以下结论。在添加了蟹壳几丁质或含几丁质的扩展青霉菌丝体的土壤微宇宙系统中，该菌株表达克隆的外切几丁质酶O1基因，并产生大量59 kDa的外切几丁质酶。该酶优先通过其结合结构域附着于土壤或液体培养物的沉淀上。相比之下，47 kDa、40 kDa和25 kDa的截短形式可以很容易地从土壤中提取出来。59 kDa酶及其截短形式的相对比例因几丁质来源而异，在土壤和液体培养物中有所不同。
