Bacillus subtilis EdmS (formerly PgsE) participates in the maintenance of episomes

- Genetic analysis of Bacillus subtilis edmSwas carried out.
- Membranous EdmS protein participated in the appearance of EDM.
- EdmS is constituted of two distinct domains.
- Homogeneous and heterogeneous EDM were further examined.
- EdmS can serve as a potent probe for exploring novel EDM systems.

Extrachromosomal DNA maintenance (EDM) is an important process in molecular breeding and for various applications in the construction of genetically engineered microbes. Here we describe a novel Bacillus subtilis gene involved in EDM function called edmS (formerly pgsE). Functional gene regions were identified using molecular genetics techniques. We found that EdmS is a membrane-associated protein that is crucial for EDM. We also determined that EdmS can change a plasmid vector with an unstable replicon and worse-than-random segregation into one with better-than-random segregation, suggesting that the protein functions in the declustering and/or partitioning of episomes. EdmS has two distinct domains: an N-terminal membrane-anchoring domain and a C-terminal assembly accelerator-like structure, and mutational analysis of edmS revealed that both domains are essential for EDM. Further studies using cells of Bacillus megaterium and itsedmS (formerly capE) gene implied that EdmS has potential as a molecular probe for exploring novel EDM systems.