The fate of the Blal repressor during the induction of the Bacillus licheniformis BlaP β-lactamase
The fate of the Blal repressor during the induction of the Bacillus licheniformis BlaP β-lactamase
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DOI：
10.1046/j.1365-2958.2002.02888.x
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发表时间：
2002-05-01
影响因子：
3.6
通讯作者：
Joris, B
中科院分区：
文献类型：
--
作者：
Filée, P;Benlafya, K;Joris, B
β-内酰胺抗生素对金黄色葡萄球菌BlaZ和地衣芽孢杆菌749/1 BIaP β-内酰胺酶的诱导根据类似的过程发生。在这两种细菌中，blal和blaR 1基因的产物具有高度的序列同源性，并分别作为阻遏物和青霉素传感器。在S.在金黄色葡萄球菌中，在添加诱导剂后，负控制BlaZ表达的BlaI阻遏物被降解。在本研究中，我们跟踪了B中β-内酰胺酶诱导过程中Blal的命运。地衣芽孢杆菌749/l和携带pDML 995质粒的重组枯草芽孢杆菌168菌株，pDML 995质粒携带B。地衣芽孢杆菌blaP、blaI和blaR 1基因。与B的情况相反。地衣749/l，B中β-内酰胺酶诱导。subtilis 168/pDML 995的表达与BlaI的蛋白水解不相关。为了排除SDS-PAGE检测不到的分子变异，用未诱导或诱导B的细胞提取物进行二维凝胶电泳。subtilis 168/pDML 995细胞。在诱导的细胞中没有观察到Blal等电点的变化，而DNA结合特性丢失。用二硫代双（琥珀酰亚胺基丙酸酯）的交联实验证实，在未诱导的重组B.在枯草杆菌细胞中，Blat作为同源二聚体存在，并且这种情况在诱导条件下没有改变。后者的结果是不兼容的机制，通过蛋白水解失活的Blal，并表明，失活的Blal的结果从一个非共价修饰的共激活剂和随后的蛋白水解的Blal可能是一个次要的现象。除了这种共激活剂的存在，我们的研究结果表明，青霉素应激的存在也需要充分诱导β-内酰胺酶的生物合成。
The induction of the Staphylococcus aureus BlaZ and Bacillus licheniformis 749/l BIaP beta-lactamases by beta-lactam antibiotics occurs according to similar processes. In both bacteria, the products of the blal and blaR1 genes share a high degree of sequence homology and act as repressors and penicillin-sensory transducers respectively. It has been shown in S. aureus that the Blal repressor, which controls the expression of BlaZ negatively, is degraded after the addition of the inducer. In the present study, we followed the fate of Blal during beta-lactamase induction in B. licheniformis 749/l and in a recombinant Bacillus subtilis 168 strain harbouring the pDML995 plasmid, which carries the B. licheniformis blaP, blal and blaR1 genes. In contrast to the situation in B. licheniformis 749/l, beta-lactamase induction in B. subtilis 168/pDML995 was not correlated with the proteolysis of Blal. To exclude molecular variations undetectable by SDS-PAGE, two-dimensional gel electrophoresis was performed with cellular extracts from uninduced or induced B. subtilis 168/pDML995 cells. No variation in the Blal isoelectric point was observed in induced cells, whereas the DNA-binding property was lost. Cross-linking experiments with dithiobis(succimidylpropionate) confirmed that, in uninduced recombinant B. subtilis cells, Blat was present as a homodimer and that this situation was not altered in induced conditions. This latter result is incompatible with a mechanism of inactivation of Blal by proteolysis and suggests that the inactivation of Blal results from a non-covalent modification by a co-activator and that the subsequent proteolysis of Blal might be a secondary phenomenon. In addition to the presence of this co-activator, our results show that the presence of penicillin stress is also required for full induction of beta-lactamase biosynthesis.