MazF is a sequence-specific endoribonuclease that is widely conserved in bacteria and archaea. Here, we found an MazF homologue (MazF-lp; LPO-p0114) in Legionella pneumophila. The mazF-lp gene overlaps 14 base pairs with the upstream gene mazE-lp (MazE-lp; LPO-p0115). The induction of mazF-lp caused cell growth arrest, while mazE-lp co-induction recovered cell growth in Escherichia coli. In vivo and in vitro primer extension experiments showed that MazF-lp is a sequence-specific endoribonuclease cleaving RNA at AACU. The endoribonuclease activity of purified MazF-lp was inhibited by purified MazE-lp. We found that MazE-lp and the MazEF-lp complex specifically bind to the palindromic sequence present in the 5'-untranslated region of the mazEF-lp operon. MazE-lp and MazEF-lp both likely function as a repressor for the mazEF-lp operon and for other genes, including icmR, whose gene product functions as a secretion chaperone for the IcmQ pore-forming protein, by specifically binding to the palindromic sequence in 5'-UTR of these genes.

中文翻译：

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鉴定在肺炎军团菌中MazF同源物，该菌在AACU序列处切割RNA。

MazF是一种序列特异性内切核糖核酸酶，在细菌和古细菌中广泛保守。在这里，我们在嗜肺军团菌中发现了一个MazF同源物（MazF-lp; LPO-p0114）。mazF-lp基因与上游基因mazE-lp（MazE-lp; LPO-p0115）重叠14个碱基对。mazF-lp的诱导引起细胞生长停滞，而mazE-lp的共诱导恢复了大肠杆菌中的细胞生长。体内和体外引物延伸实验表明，MazF-lp是在AACU处切割RNA的序列特异性内切核糖核酸酶。纯化的MazE-lp抑制了纯化的MazF-lp的核糖核酸内切酶活性。我们发现，MazE-lp和MazEF-lp复合物特异性结合到存在于mazEF-lp操纵子5'-非翻译区的回文序列。