Analysis of the Mycobacterium bovis hsp60 promoter activity in recombinant Mycobacterium avium
- 作者：Batoni ; Giovanna ; Maisetta ; Giuseppantonio ; Florio ; Walter ; Freer ; Giulia ; Campa ; Mario ; Senesi ; Sonia
- 关键词：Mycobacterium avium ; hsp60 promoter ; β ; -Galactosidase ; Intracellular growth
- 刊名：FEMS Microbiology Letters
- 出版年：1998
- 期刊代码：34_03781097
- 类别：imm
- 出版时间：December 1, 1998
- 卷：169
- 期：1
- 页码：117-124
- 文件大小：222 K
摘要
A clinical isolate of Mycobacterium avium was transformed with a new shuttle plasmid containing the Escherichia coli β-galactosidase reporter gene under the control of the Mycobacterium bovis bacillus Calmette-Guérin (BCG) hsp60 promoter. β-Galactosidase activity was assayed spectrophotometrically in bacterial homogenates of the recombinant strain (M. avium::lacZ) and used for quantification of the hsp60 promoter strength in different conditions of extra- and intracellular growth. Very low levels of β-galactosidase were recorded during the exponential phase of in vitro growth, while they increased progressively during the late exponential and stationary phases. A significant increase in enzyme activity was also induced in exponentially growing cells by shifting the incubation temperature from 37 to 45°C, but not from 37 to 42°C nor from 30 to 42°C. No induction of the promoter was observed by adding hydrogen peroxide to the cultures. Finally, β-galactosidase levels were quantified during growth of M. avium::lacZ in murine macrophages. Soon after phagocytosis and, to a lesser extent at 1, 5 and 7 days after infection, increased levels of bacterial β-galactosidase were observed indicating an increment in transcriptional activity of hsp60 promoter both at early phases of infection and during the course of intracellular growth.