Cervoni Matteo, Sposato Davide, Lo Sciuto Alessandra, Imperi Francesco
Department of Science, Roma Tre University, 00146 Rome, Italy.
IRCCS Fondazione Santa Lucia, 00179 Rome, Italy.
Antibiotics (Basel). 2023 Jan 18;12(2):200. doi: 10.3390/antibiotics12020200.
has the genetic potential to acquire colistin resistance through the modification of lipopolysaccharide by the addition of 4-amino-4-deoxy-L-arabinose (L-Ara4N) or phosphoethanolamine (PEtN), mediated by the operon or the gene, respectively. However, in vitro evolution experiments and genetic analysis of clinical isolates indicate that lipopolysaccharide modification with L-Ara4N is invariably preferred over PEtN addition as the colistin resistance mechanism in this bacterium. Since little is known about regulation in , we generated luminescent derivatives of the reference strain PAO1 to monitor and promoter activity. We performed transposon mutagenesis assays to compare the likelihood of acquiring mutations leading to or induction and to identify regulators. The analysis revealed that was slightly induced under certain stress conditions, such as arginine or biotin depletion and accumulation of the signal molecule diadenosine tetraphosphate, but the induction did not confer colistin resistance. Moreover, we demonstrated that spontaneous mutations leading to colistin resistance invariably triggered rather than expression, and that was not induced in resistant mutants upon colistin exposure. Overall, these results suggest that the contribution of to colistin resistance in may be limited by regulatory restraints.
具有通过分别由操纵子或基因介导的添加4-氨基-4-脱氧-L-阿拉伯糖（L-Ara4N）或磷酸乙醇胺（PEtN）来修饰脂多糖从而获得对黏菌素耐药性的遗传潜力。然而，体外进化实验和临床分离株的遗传分析表明，在这种细菌中，作为黏菌素耐药机制，用L-Ara4N修饰脂多糖总是比添加PEtN更受青睐。由于对其调控了解甚少，我们构建了参考菌株PAO1的发光衍生物以监测和启动子活性。我们进行了转座子诱变试验，以比较获得导致或诱导的突变的可能性，并鉴定调控因子。分析表明，在某些应激条件下，如精氨酸或生物素耗竭以及信号分子四磷酸二腺苷积累时，会有轻微诱导，但这种诱导并未赋予黏菌素耐药性。此外，我们证明导致黏菌素耐药性的自发突变总是触发而不是表达，并且在黏菌素暴露后耐药突变体中未被诱导。总体而言，这些结果表明，对黏菌素耐药性的贡献可能受到调控限制的限制。
