Rasis Michal, Ziklo Noa, Salama Paul
Innovation Department, Sharon Personal Care Ltd., Eli Horovitz St. 4, Rehovot 7608810, Israel.
Microorganisms. 2025 Jul 10;13(7):1636. doi: 10.3390/microorganisms13071636.
Niacinamide was recently shown to directly interact with bacterial DNA and interfere with cell replication; niacinamide mode of interaction and efficacy as a natural anti-microbial molecule were also described. The aim of this study is to elucidate the exact binding mechanism of niacinamide to microbial DNA. Intercalation is a binding mode where a small planar molecule, such as niacinamide, is inserted between base pairs, causing structural changes in the DNA. Melting curve analysis with various intercalating dyes demonstrated that niacinamide interaction with bacterial DNA reduces its melting temperature in a linear dose-dependent manner. Niacinamide's effect on the melting temperature was found to be % GC-dependent, while purine stretches were also found to influence the binding kinetics. Finally, fluorescent intercalator displacement (FID) assays demonstrated that niacinamide strongly reduces SYBR Safe signal in a dose-dependent manner. Interestingly, competition assays with a minor groove binder also reduced Hoechst signal but in a non-linear manner, which can be attributed to strand lengthening and unwinding following niacinamide intercalation. Taken altogether; our results suggest a "disruptive intercalation" as the mode of interaction of niacinamide with bacterial DNA. Formation of locally destabilized DNA portions by niacinamide might interfere with protein-DNA interaction and potentially affect several crucial bacterial cellular processes, e.g., DNA repair and replication, subsequently leading to cell death.
烟酰胺最近被证明可直接与细菌DNA相互作用并干扰细胞复制；还描述了烟酰胺作为一种天然抗菌分子的相互作用模式和功效。本研究的目的是阐明烟酰胺与微生物DNA的确切结合机制。嵌入是一种结合模式，其中一个小的平面分子，如烟酰胺，插入碱基对之间，导致DNA结构变化。用各种嵌入染料进行的熔解曲线分析表明，烟酰胺与细菌DNA的相互作用以线性剂量依赖性方式降低其熔解温度。发现烟酰胺对熔解温度的影响取决于GC含量，同时还发现嘌呤序列也会影响结合动力学。最后，荧光嵌入剂置换（FID）分析表明，烟酰胺以剂量依赖性方式强烈降低SYBR Safe信号。有趣的是，与小沟结合剂的竞争分析也降低了Hoechst信号，但方式是非线性的，这可归因于烟酰胺嵌入后链的延长和解旋。综上所述，我们的结果表明“破坏性嵌入”是烟酰胺与细菌DNA的相互作用模式。烟酰胺形成局部不稳定的DNA部分可能会干扰蛋白质-DNA相互作用，并可能影响几个关键的细菌细胞过程，例如DNA修复和复制，随后导致细胞死亡。
