Temasek Life Sciences Laboratory, Singapore, Singapore.
Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
Commun Biol. 2023 Jan 28;6(1):118. doi: 10.1038/s42003-023-04496-9.
Although Clostridium novyi-NT is an anti-cancer bacterial therapeutic which germinates within hypoxic tumors to kill cancer cells, the actual germination triggers for C. novyi-NT are still unknown. In this study, we screen candidate germinants using combinatorial experimental designs and discover by serendipity that D-valine is a potent germinant, inducing 50% spore germination at 4.2 mM concentration. Further investigation revealed that five D-valine analogs are also germinants and four of these analogs are enantiomeric pairs. This stereoflexible effect of L- and D-amino acids shows that spore germination is a complex process where enantiomeric interactions can be confounders. This study also identifies L-cysteine as a germinant, and hypoxanthine and inosine as co-germinants. Several other amino acids promote (L-valine, L-histidine, L-threonine and L-alanine) or inhibit (L-arginine, L-glycine, L-lysine, L-tryptophan) germination in an interaction-dependent manner. D-alanine inhibits all germination, even in complex growth media. This work lays the foundation for improving the germination efficacy of C. novyi-NT spores in tumors.
虽然梭菌 C. novyi-NT 是一种抗肿瘤的细菌治疗药物，它在缺氧肿瘤中发芽以杀死癌细胞，但 C. novyi-NT 的实际发芽触发因素仍不清楚。在这项研究中，我们使用组合实验设计筛选候选发芽剂，并偶然发现 D-缬氨酸是一种有效的发芽剂，在 4.2mM 浓度下诱导 50%的孢子发芽。进一步的研究表明，五种 D-缬氨酸类似物也是发芽剂，其中四种是对映异构体对。L-和 D-氨基酸的这种立体灵活性表明，孢子发芽是一个复杂的过程，其中对映体相互作用可能是混杂因素。这项研究还确定 L-半胱氨酸是一种发芽剂，次黄嘌呤和肌苷是共同发芽剂。其他几种氨基酸以相互依赖的方式促进（L-缬氨酸、L-组氨酸、L-苏氨酸和 L-丙氨酸）或抑制（L-精氨酸、L-甘氨酸、L-赖氨酸、L-色氨酸）发芽。D-丙氨酸抑制所有的发芽，即使在复杂的生长培养基中也是如此。这项工作为提高 C. novyi-NT 孢子在肿瘤中的发芽效果奠定了基础。
