Bricker J, Mulks M H, Plaut A G, Moxon E R, Wright A
Proc Natl Acad Sci U S A. 1983 May;80(9):2681-5. doi: 10.1073/pnas.80.9.2681.
Haemophilus influenzae is one of several bacterial pathogens known to release IgA1 proteases into the extracellular environment. Each H. influenzae isolate produces one of at least three distinct types of these enzymes that differ in the specific peptide bond they cleave in the hinge region of human IgA1. We have isolated the gene specifying type 1 IgA1 protease from a total genomic library of H. influenzae, subcloned it into plasmid vectors, and introduced these vectors into Escherichia coli K-12. The enzyme synthesized by E. coli was active and had the same specificity as that of the H. influenzae donor. Unlike that of the donor, E. coli protease activity accumulated in the periplasm rather than being transported extracellularly. The position of the protease gene in H. influenzae DNA and its direction of transcription was approximated by deletion mapping. Tn5 insertions, and examination of the polypeptides synthesized by minicells. A 1-kilobase probe excised from the IgA1 protease gene hybridized with DNA restriction fragments of all H. influenzae serogroups but not with DNA of a nonpathogenic H. parainfluenzae species known to be IgA1 protease negative.
流感嗜血杆菌是已知的几种能将IgA1蛋白酶释放到细胞外环境中的细菌病原体之一。每株流感嗜血杆菌至少能产生三种不同类型的这类酶中的一种，它们在人IgA1铰链区切割的特定肽键不同。我们从流感嗜血杆菌的全基因组文库中分离出了编码1型IgA1蛋白酶的基因，将其亚克隆到质粒载体中，并将这些载体导入大肠杆菌K-12。大肠杆菌合成的这种酶具有活性，且与流感嗜血杆菌供体的酶具有相同的特异性。与供体不同的是，大肠杆菌的蛋白酶活性积累在周质中，而不是被转运到细胞外。通过缺失图谱分析、Tn5插入以及对小细胞合成的多肽进行检测，大致确定了流感嗜血杆菌DNA中蛋白酶基因的位置及其转录方向。从IgA1蛋白酶基因中切下的一个1千碱基的探针与所有流感嗜血杆菌血清群的DNA限制性片段杂交，但不与已知为IgA1蛋白酶阴性的非致病性副流感嗜血杆菌的DNA杂交。
