Charles-Orszag Arthur, Lord Samuel J, Herrera Nadia, Strauskulage Luke, Bhowmick Arghya, Goddard Tom, Wassmer Bianca, van Wolferen Marleen, Asper Garrison, Flis Amy, Rodriguez Johnny, Redding Sy, Rosenberg Oren, Albers Sonja-Verena, Mullins R Dyche
Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA.
Department of Microbiology and Molecular Genetics, College of Biological Sciences, University of California Davis, Davis, CA, USA.
bioRxiv. 2025 May 21:2025.04.15.649018. doi: 10.1101/2025.04.15.649018.
Archaeal operons are thought to promote chromosome segregation, but their mechanism remains unknown. We employ comparative genomics, structural biology, genetic knockouts, and quantitative cell biology to investigate how SegA and SegB proteins work together to segregate chromosomes in the thermophilic archaeon . , SegB binds a centromeric DNA sequence adjacent to the operon, and forms a distinct focus on each segregating chromosome. SegA, a ParA-like ATPase, binds DNA non-specifically and promotes chromosome compaction and segregation . During division, SegA shifts from chromosome-associated puncta to form a single, elongated figure that runs between separating SegB foci. Late in division, SegA retreats to regions surrounding separated SegB foci. Elongated SegA figures appear in knockout cells but no longer lie perpendicular to the division plane. We propose that SegA and SegB interact to form a bipolar, DNA-segregating structure radically different from bacterial ParABS systems.
古菌操纵子被认为有助于染色体分离，但其机制仍不清楚。我们运用比较基因组学、结构生物学、基因敲除和定量细胞生物学方法，来研究SegA和SegB蛋白如何协同作用，以在嗜热古菌中分离染色体。SegB结合操纵子附近的着丝粒DNA序列，并在每条分离的染色体上形成一个独特的焦点。SegA是一种类似ParA的ATP酶，它非特异性地结合DNA，并促进染色体的压缩和分离。在分裂过程中，SegA从与染色体相关的小点转变为形成一个单一的、细长的结构，该结构在分离的SegB焦点之间延伸。在分裂后期，SegA退回到分离的SegB焦点周围的区域。细长的SegA结构出现在基因敲除细胞中，但不再与分裂平面垂直。我们提出，SegA和SegB相互作用形成一种双极的、DNA分离结构，与细菌的ParABS系统截然不同。
