Advanced Genetic Sciences, Inc., 6701 San Pablo Avenue, Oakland, CA 94608, USA.
EMBO J. 1986 Mar;5(3):467-73. doi: 10.1002/j.1460-2075.1986.tb04235.x.
Analysis of clones isolated from a cosmid DNA library indicates that the Serratia marcescens chromosome contains at least two genes, chiA and chiB, which encode distinct secreted forms of the enzyme chitinase. These genes have been characterized by inspection of chitinase activity and secreted proteins in Escherichia coli strains containing subclones of these cosmids. The two chitinase genes show no detectable homology to each other. DNA sequence analysis of one of the genes predicts an amino acid sequence with an N-terminal signal peptide typical of genes encoding secreted bacterial proteins. This gene was mutagenized by cloning a neomycin phosphotransferase gene within its coding region, and the insertion mutation was recombined into the parental S. marcescens strain. The resulting chiA mutant transconjugant showed reduced chitinase production, reduced inhibition of fungal spore germination and reduced biological control of a fungal plant pathogen.
从粘粒 DNA 文库中分离出的克隆分析表明，粘质沙雷氏菌染色体至少包含两个基因，chiA 和 chiB，它们分别编码该酶几丁质酶的不同分泌形式。这些基因的特征是通过检查含有这些粘粒亚克隆的大肠杆菌菌株中的几丁质酶活性和分泌蛋白来确定的。这两个几丁质酶基因彼此之间没有明显的同源性。对其中一个基因的 DNA 序列分析预测了一种具有 N 端信号肽的氨基酸序列，该信号肽是编码分泌细菌蛋白的基因的典型特征。通过在该基因的编码区中克隆新霉素磷酸转移酶基因，对该基因进行了诱变，并将插入突变重组到亲本粘质沙雷氏菌菌株中。产生的 chiA 突变型转导子显示出几丁质酶产量降低、对真菌孢子萌发的抑制作用降低以及对真菌植物病原体的生物防治作用降低。
