Ali Samson, Koh Adrian, Popp David, Tanaka Kotaro, Kitaoku Yoshihito, Miyazaki Naoyuki, Iwasaki Kenji, Mitsuoka Kaoru, Robinson Robert C, Narita Akihiro
Research Institute for Interdisciplinary Science, Okayama University, Okayama, Japan; Institute of Molecular and Cell Biology, A∗STAR (Agency for Science, Technology and Research), Biopolis, Singapore.
Institute of Molecular and Cell Biology, A∗STAR (Agency for Science, Technology and Research), Biopolis, Singapore; Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.
J Biol Chem. 2025 Jul;301(7):110351. doi: 10.1016/j.jbc.2025.110351. Epub 2025 Jun 9.
ParMs generally exist on low-copy number plasmids where they contribute to plasmid segregation and stable inheritance. We carried out bioinformatics analysis, which indicated that ParM genes are not only confined to plasmids but are also occasionally found on genomes. Here we report the discovery and characterization of two chromosome-encoded ParMs (cParMs) from the genomes of Desulfitobacterium hafniense (Dh-cParM1) and Clostridium botulinum (Cb-cParM). Both cParMs form filaments, exhibit nucleotide hydrolysis, and possess characteristic ParM subunit structures. Dh-cParM1 forms single and tightly coupled double filaments and is highly conserved on the chromosomes of five of six Desulfitobacterium species. Interestingly, these bacteria have not been reported to harbor plasmids. Cb-cParM possesses unique properties. Its filaments were stable after nucleotide hydrolysis and Pi release, and its ParR (Cb-cParR) did not affect the initial phase of Cb-cParM polymerization but displayed properties of a depolymerization factor for mature filaments. These results indicate functional, polymerizing ParMs can be encoded on genomes, suggesting that ParM roles may extend to other functions beyond plasmid segregation.
ParM通常存在于低拷贝数质粒上，在质粒分离和稳定遗传过程中发挥作用。我们进行了生物信息学分析，结果表明ParM基因不仅局限于质粒，偶尔也会在基因组中发现。在此，我们报告了从嗜热栖热脱硫杆菌（Dh-cParM1）和肉毒梭菌（Cb-cParM）基因组中发现并鉴定出两种染色体编码的ParM（cParM）。两种cParM均能形成细丝，具有核苷酸水解活性，并拥有典型的ParM亚基结构。Dh-cParM1形成单丝和紧密相连的双丝，在六种嗜热栖热脱硫杆菌中的五种的染色体上高度保守。有趣的是，尚未有报道称这些细菌含有质粒。Cb-cParM具有独特的特性。其细丝在核苷酸水解和无机磷酸释放后仍保持稳定，其ParR（Cb-cParR）不影响Cb-cParM聚合的初始阶段，但对成熟细丝表现出解聚因子的特性。这些结果表明，具有功能的聚合型ParM可以在基因组中编码，这表明ParM的作用可能扩展到质粒分离以外的其他功能。
