Juarez A, Härtlein M, Goebel W
J Bacteriol. 1984 Oct;160(1):161-8. doi: 10.1128/jb.160.1.161-168.1984.
Operon and gene fusions between lacZ and the hemolysin genes, hlyC and hlyA, were performed. These two genes are essential for the synthesis of active hemolysin and are transcribed from a common promoter (p1). Whereas the amount of hemolysin produced in Escherichia coli is not changed by altering the hly gene dose, beta-galactosidase activity follows the gene dosage in both types of fusions when lacZ comes under the control of p1. This indicates that hemolysin is not negatively regulated on the transcription or translation level. The products of the gene fusions hlyC::lacZ and hlyA::lacZ were identified in maxicells as stable proteins of 146,000 and 220,000 daltons, respectively. Both fusion proteins possess beta-galactosidase activity indicating that the performed fusions of lacZ to the hly genes do not destroy the reading frame of hlyC and hlyA. The fusion proteins HlyC-beta-gal and HlyA-beta-gal were predominantly detected in the cytoplasm, confirming previous data which suggested that the primary gene products of hlyC and hlyA are not transported across the cytoplasmic membrane.
构建了lacZ与溶血素基因hlyC和hlyA之间的操纵子和基因融合体。这两个基因对于活性溶血素的合成至关重要，并且从一个共同的启动子（p1）转录。虽然在大肠杆菌中产生的溶血素量不会因改变hly基因剂量而改变，但当lacZ受p1控制时，在两种类型的融合体中β-半乳糖苷酶活性都遵循基因剂量。这表明溶血素在转录或翻译水平上不受负调控。在最大细胞中鉴定出基因融合体hlyC::lacZ和hlyA::lacZ的产物分别为146,000和220,000道尔顿的稳定蛋白质。两种融合蛋白都具有β-半乳糖苷酶活性，表明所进行的lacZ与hly基因的融合没有破坏hlyC和hlyA的阅读框。融合蛋白HlyC-β-gal和HlyA-β-gal主要在细胞质中检测到，这证实了先前的数据，即hlyC和hlyA的主要基因产物不会穿过细胞质膜运输。
