Deletion of mazF increases Staphylococcus aureus biofilm formation in an ica-dependent manner
Deletion of mazF increases Staphylococcus aureus biofilm formation in an ica-dependent manner
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DOI：
10.1093/femspd/ftx026
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发表时间：
2017-07-01
影响因子：
3.3
通讯作者：
Inouye, Masayori
中科院分区：
文献类型：
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作者：
Kato, Fuminori;Yabuno, Yusuke;Inouye, Masayori
毒素-抗毒素(TA)系统由一种抑制基本细胞过程(如DNA复制、转录、膜完整性)的毒素和其同源抗毒素中和毒素的作用组成。金黄色葡萄球菌含有两种染色体编码的TA系统，即编码UACAU特异性mRNA干扰酶的mazEF(Sa)和编码核糖体依赖的内切核酸酶系统的两个类似的yefM-yoeB(Sa)基因。然而，目前对MazEF(Sa)和YefM-YoeB(Sa)在金黄色葡萄球菌中的生理作用知之甚少。通过对单基因、双基因和三基因缺失突变体的表型分析，我们发现mazF(Sa)缺失导致生物膜形成增加。随后，转录分析表明，在mazF(Sa)缺失突变体中，细胞间黏附素(ICA)基因icaADBC的表达增加。MazF(Sa)/icaADBC双基因缺失和遗传互补方法提供了令人信服的证据，证明生物膜形成的增加是由于icaADBC编码蛋白合成的多糖胞间粘附素增加所致。此外，通过利用MazF(Sa)保守活性残基上的丙氨酸取代，我们的结果表明ICA介导的生物膜的形成依赖于MazF(Sa)的mRNA干扰酶活性。这些发现不仅为MazEF(Sa)在金黄色葡萄球菌中的生理作用提供了新的见解，也为ICA依赖的生物膜形成的调控机制提供了新的见解。
Toxin-antitoxin (TA) systems are composed of a toxin that inhibits an essential cellular process (e.g. DNA replication, transcription, membrane integrity) and its cognate antitoxin that neutralizes the effect of the toxin. Staphylococcus aureus harbors two types of chromosomally encoded TA systems, namely mazEF(sa) encoding a UACAU-specific mRNA interferase and two paralogous genes of yefM-yoeB(sa) encoding a ribosome-dependent endoribonuclease system. However, little is known about the physiological role of MazEF(sa) and YefM-YoeB(sa) in S. aureus. Upon characterizing the phenotypes of single, double and triple gene deletion mutants, we found that mazF(sa) deletion led to increased biofilm formation. Subsequently, transcriptional analysis revealed that expression of intercellular adhesin (ica) gene, icaADBC, increased in a mazF(sa) deletion mutant. mazF(sa)/icaADBC double gene deletion and genetic complementation approaches provided convincing evidence that increased biofilm formation was caused by an increase in polysaccharide intercellular adhesin synthesized by icaADBC-encoded proteins. Furthermore, through the use of alanine substitutions at the conserved active residues of MazF(sa), our results suggested that ica-mediated biofilm formation depended on the mRNA interferase activity of MazF(sa). These findings give new insights not only into the physiological role of MazEF(sa) in S. aureus, but also into the regulatory mechanism of ica-dependent biofilm formation.