Rhodomyrtone has been recently demonstrated to possess a novel antibiotic mechanism of action against Gram-positive bacteria which involved the multiple targets, resulting in the interference of several bacterial biological processes including the cell division. The present study aims to closely look at the downstream effect of rhodomyrtone treatment on nucleoid segregation in Streptococcus suis, an important zoonotic pathogen. The minimum inhibition concentration (MIC) and the minimum bactericidal concentration (MBC) values of rhodomyrtone against the recombinant S. suis ParB-GFP, a nucleoid segregation reporter strain, were 0.5 and 1 µg/ml, respectively, which were equivalent to the potency of vancomycin. Using the fluorescence live-cell imaging, we demonstrated that rhodomyrtone at 2× MIC caused incomplete nucleoid segregation and septum misplacement, leading to the generation of anucleated cells. FtsZ immune-staining of rhodomyrtone-treated S. suis for 30 min revealed that the large amount of FtsZ was trapped in the region of high fluidity membrane and appeared to be able to polymerize to form a complete Z-ring. However, the Z-ring was shifted away from the midcell. Transmission electron microscopy further confirmed the disruption of nucleoid segregation and septum misplacement at 120 min following the rhodomyrtone treatment. Asymmetric septum formation resulted in either generation of minicells without nucleoid, septum formed over incomplete segregated nucleoid (guillotine effect), or formation of multi-constriction of Z-ring within a single cell. This finding spotlights on antibacterial mechanism of rhodomyrtone involves the early stage in bacterial cell division process.

最近已证明，Rhodomyrtone具有抵抗涉及多个靶标的革兰氏阳性细菌的新型抗生素作用机制，从而导致干扰包括细胞分裂在内的多种细菌生物学过程。本研究旨在密切观察罗丹明酮治疗对猪链球菌（一种重要的人畜共患病原体）中核苷酸分离的下游影响。Rhodomyrtone对重组猪链球菌的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）值ParB-GFP，一种核苷分离报道株，分别为0.5和1 µg / ml，相当于万古霉素的效价。使用荧光活细胞成像，我们证明了2×MIC的Rhodomyrtone会导致不完全的核苷酸分离和隔垫错位，从而导致无核细胞的生成。罗丹明酮处理的猪链球菌的FtsZ免疫染色持续30分钟表明，大量的FtsZ被捕获在高流动性膜的区域中并且似乎能够聚合形成完整的Z形环。但是，Z形环从中单元移开了。透射电镜进一步证实了在红景天处理后120分钟时核苷酸样分离和隔膜错位的破坏。不对称的隔膜形成会导致无核小细胞生成，在不完整的分离核苷上形成隔膜（断头台效应）或在单个细胞内形成多环Z环。这一发现对红景天的抗菌机制的关注涉及细菌细胞分裂过程的早期阶段。