Biological role of the pneumococcal amidase. Cloning of the lytA gene in Streptococcus pneumoniae.-猫眼课题宝

肺炎球菌酰胺酶的生物学作用。

DOI：

10.1111/j.1432-1033.1987.tb11172.x

发表时间：

1987

期刊：

European journal of biochemistry

影响因子：

通讯作者：

中科院分区：

文献类型：

作者：

C. Ronda;J. L. García;Ernesto García;J. Sánchez;R. Lopez

以肺炎球菌质粒pLS1为载体，构建了含有编码肺炎球菌n -乙酰muramyl - l-丙氨酸酰胺酶的lytA基因的重组质粒pRG2。通过遗传转化将pRG2引入到lytA基因完全缺失的肺炎链球菌（M31）突变体中。转化后的菌株（M51）以正常的生长速率生长为“diplo”细胞，并在生长的指数期结束时进行自溶，这两个特性在被删除的突变体M31中已经失去。当细胞在含胆碱的培养基中生长时，M51在指数期结束时裂解得非常快，这可能是因为与易于裂解的菌株M11相比，该菌株中存在更高水平的酰胺酶活性。这些结果表明，在指数期，质粒连接基因的表达处于细胞控制的机制下。我们的研究结果表明，肺炎球菌酰胺酶的生理作用是在细胞分裂结束时催化子细胞分离产生二倍体细胞；此外，我们还证实了这种自溶素在β -内酰胺类抗生素的细菌溶解性质中的基本作用。

A pneumococcal recombinant plasmid, pRG2, containing the lytA gene that codes for the pneumococcal N-acetylmuramoyl-L-alanine amidase has been constructed using the pneumococcal plasmid pLS1 as a vector. pRG2 was introduced by genetic transformation into a mutant of Streptococcus pneumoniae (M31) that has a complete deletion of the lytA gene. The transformed strain (M51) grew at a normal growth rate as 'diplo' cells and underwent autolysis at the end of the exponential phase of growth, two properties that had been lost in the deleted mutant M31. M51 lysed very rapidly at the end of the exponential phase when the cells were grown in choline-containing medium probably because of the higher level of amidase activity present in this strain as compared to the lysis-prone strain M11. These findings show that the expression of the plasmid-linked gene was placed under the mechanism(s) of control of the cell during the exponential phase. Our results demonstrate that the physiological role of the pneumococcal amidase was to catalyze the separation of the daughter cells at the end of the cell division to produce diplo cells; in addition we have also confirmed the basic role of this autolysin in the bacteriolytic nature of beta-lactam antibiotics.

Cloning of chromosomal genes in Streptococcus pneumoniae.