Biological Sciences Department, Corporate Research Laboratories, Monsanto Company, St. Louis, Missouri 63198.
Appl Environ Microbiol. 1986 Mar;51(3):504-9. doi: 10.1128/aem.51.3.504-509.1986.
Serratia marcescens, a chitinase-producing microorganism, was shown to produce five unique chitinolytic proteins with subunit molecular masses of 21, 36, 48, 52, and 57 kilodaltons. A cosmid library of S. marcescens DNA was constructed in the broad-host-range cosmid pLAFR1 and screened in Escherichia coli for clones capable of degrading chitin. A total of four independent clones (22- to 27-kilobase inserts) were isolated, characterized by restriction endonuclease digestion, and shown to share a common 9.5-kilobase EcoR1 fragment apparently encoding the same 57-kilodalton chitinase, the most abundant chitinase produced by S. marcescens. Chitinase expression from these constructs in both E. coli and Pseudomonas fluorescens 701E1 is apparently driven by an S. marcescens promoter. The significantly higher chitinase levels produced in E. coli relative to those in P. fluorescens 701E1 suggest that E. coli may recognize this promoter sequence more efficiently than P. fluorescens.
粘质沙雷氏菌是一种产壳聚糖酶的微生物，被证明能产生五种具有独特结构的壳聚糖酶，其亚基分子量分别为 21、36、48、52 和 57 千道尔顿。构建了粘质沙雷氏菌 DNA 的 cosmid 文库，该文库位于广宿主范围的 cosmid pLAFR1 中，并在大肠杆菌中进行筛选，以寻找能够降解壳聚糖的克隆。共分离到四个独立的克隆（22-27kb 插入片段），通过限制性内切酶消化进行了表征，并显示它们共享一个共同的 9.5kb EcoR1 片段，显然编码相同的 57 千道尔顿壳聚糖酶，这是粘质沙雷氏菌产生的最丰富的壳聚糖酶。这些构建体在大肠杆菌和荧光假单胞菌 701E1 中的表达显然是由粘质沙雷氏菌启动子驱动的。与荧光假单胞菌 701E1 相比，大肠杆菌中壳聚糖酶的产量明显更高，这表明大肠杆菌可能比荧光假单胞菌更有效地识别这个启动子序列。
