Bhat Supriya V, Kamencic Belma, Körnig André, Shahina Zinnat, Dahms Tanya E S
Department of Chemistry and Biochemistry, University of Regina, Regina, SK, Canada.
JPK Instruments AG, Berlin, Germany.
Front Microbiol. 2018 Feb 1;9:44. doi: 10.3389/fmicb.2018.00044. eCollection 2018.
is a robust, easily adaptable and culturable bacterium , and a model bacterium for studying the impact of xenobiotics in the environment. We have used correlative atomic force - laser scanning confocal microscopy (AFM-LSCM) to characterize the mechanisms of cellular response to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). One of the most extensively used herbicides world-wide, 2,4-D is known to cause hazardous effects in diverse non-target organisms. Sub-lethal concentrations of 2,4-D caused DNA damage in WM1074 during short exposure periods which increased significantly over time. In response to 2,4-D, FtsZ and FtsA relocalized within seconds, coinciding with the complete inhibition of cell septation and cell elongation. Exposure to 2,4-D also resulted in increased activation of the SOS response. Changes to cell division were accompanied by concomitant changes to surface roughness, elasticity and adhesion in a time-dependent manner. This is the first study describing the mechanistic details of 2,4-D at sub-lethal levels in bacteria. Our study suggests that 2,4-D arrests cell division within seconds after exposure by disrupting the divisome complex, facilitated by dissipation of membrane potential. Over longer exposures, 2,4-D causes filamentation as a result of an SOS response to oxidative stress induced DNA damage.
是一种健壮、易于适应且可培养的细菌，是研究环境中异生素影响的模式细菌。我们使用相关原子力 - 激光扫描共聚焦显微镜（AFM-LSCM）来表征细胞对除草剂2,4-二氯苯氧乙酸（2,4-D）的反应机制。2,4-D是全球使用最广泛的除草剂之一，已知会对多种非靶标生物造成有害影响。在短暴露期内，亚致死浓度的2,4-D会导致WM1074中的DNA损伤，且随着时间的推移损伤显著增加。响应2,4-D时，FtsZ和FtsA在数秒内重新定位，这与细胞分裂和细胞伸长的完全抑制同时发生。暴露于2,4-D还导致SOS反应的激活增加。细胞分裂的变化伴随着表面粗糙度、弹性和粘附性随时间的相应变化。这是第一项描述细菌中亚致死水平的2,4-D作用机制细节的研究。我们的研究表明，2,4-D在暴露后数秒内通过破坏分裂体复合物来阻止细胞分裂，这是由膜电位消散促成的。在更长时间的暴露下，2,4-D由于对氧化应激诱导的DNA损伤的SOS反应而导致细胞丝状化。
