Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Chicago, 60611, IL, USA.
Medical Scientist Training Program, Feinberg School of Medicine, Northwestern University, Chicago, 60611, IL, USA.
NPJ Biofilms Microbiomes. 2024 Oct 7;10(1):103. doi: 10.1038/s41522-024-00575-9.
DNA is the genetic code found inside all living cells and its molecular stability can also be utilized outside the cell. While extracellular DNA (eDNA) has been identified as a structural polymer in bacterial biofilms, whether it persists stably throughout development remains unclear. Here, we report that eDNA is temporarily invested in the biofilm matrix before being reclaimed later in development. Specifically, by imaging eDNA dynamics within undomesticated Bacillus subtilis biofilms, we found eDNA is produced during biofilm establishment before being globally degraded in a spatiotemporally coordinated pulse. We identified YhcR, a secreted Ca-dependent nuclease, as responsible for eDNA degradation in pellicle biofilms. YhcR cooperates with two other nucleases, NucA and NucB, to reclaim eDNA for its phosphate content in colony biofilms. Our results identify extracellular nucleases that are crucial for eDNA reclamation during biofilm development and we therefore propose a new role for eDNA as a dynamic metabolic reservoir.
DNA 是存在于所有活细胞内的遗传密码，其分子稳定性也可以在细胞外被利用。虽然细胞外 DNA（eDNA）已被鉴定为细菌生物膜中的结构聚合物，但它在整个发育过程中是否稳定存在尚不清楚。在这里，我们报告 eDNA 在发育过程中稍后被重新回收之前，暂时投入到生物膜基质中。具体来说，通过对野生型枯草芽孢杆菌生物膜内 eDNA 动态的成像，我们发现 eDNA 在生物膜形成过程中产生，然后在时空协调的脉冲中被全局降解。我们鉴定出 YhcR，一种分泌的 Ca 依赖性核酸酶，负责在菌膜生物膜中降解 eDNA。YhcR 与另外两种核酸酶 NucA 和 NucB 合作，回收 eDNA 的磷酸基团用于菌落生物膜。我们的结果确定了在生物膜发育过程中回收 eDNA 至关重要的细胞外核酸酶，因此我们提出了 eDNA 作为动态代谢储库的新作用。
