Hitchhiking on chromosomes: A persistence strategy shared by diverse selfish DNA elements

Publication date: Available online 3 February 2019Source: PlasmidAuthor(s): Soumitra Sau, Santanu Kumar Ghosh, Yen-Ting Liu, Chien-Hui Ma, Makkuni JayaramAbstractAn underlying theme in the segregation of low-copy bacterial plasmids is the assembly of a ‘segrosome’ by DNA-protein and protein-protein interactions, followed by energy-driven directed movement. Analogous partitioning mechanisms drive the segregation of host chromosomes as well. Eukaryotic extra-chromosomal elements, exemplified by budding yeast plasmids and episomes of certain mammalian viruses, harbor partitioning systems that promote their physical association with chromosomes. In doing so, they indirectly take advantage of the spindle force that directs chromosome movement to opposite cell poles. Molecular-genetic, biochemical and cell biological studies have revealed several unsuspected aspects of ‘chromosome hitchhiking’ by the yeast 2-micron plasmid, including the ability of plasmid sisters to associate symmetrically with sister chromatids. As a result, the plasmid overcomes the ‘mother bias’ experienced by plasmids lacking a partitioning system, and elevates itself to near chromosome status in equal segregation. Chromosome association for stable propagation, without direct energy expenditure, may also be utilized by a small minority of bacterial plasmids–at least one case has been reported. Given the near perfect accuracy of chromosome segregation, it is not surprising that elements residing i...
Source: Plasmid - Category: Biotechnology Source Type: research