利用細菌基因位點動態行為解析基因表現對染色體空間組織的影響

As a carrier of information, bacterial chromosome plays not only as a storage of the gene, but its optimized organization also helps the bacterial cell efficiently performs transcription, replication, and segregation in parallel. Conventionally, the chromosome is considered to be locally organized and looped into linked blubs by the associated proteins. The elastic and entropic interactions between blubs, together with the confinement of cell shape, dominate the global motion of the DNA-protein complex polymer and majorly drive the segregation during cell division. Further, based on the observation on the motion behavior of chromosome, it implies that the chromosome organization is also altered by gene expression conversely in prokaryotic cells. In this study, we examined how the expression of either the lacY or the cfp gene in the native lac operon influences adjacent chromosomal segments by fluorescently labeling loci upstream and downstream of the expressed gene. To reveal the details of the effect induced by the gene expression, the positions and the motions of the local chromosomal segments around the lactose operon have been investigated. Based on the motion behaviors of the chromosome locus pair, the relaxation and the reorganization of the local chromosomal segments have been qualitatively and quantitatively resolved. It has also indicated the expression-induced difference between the genes encoded the cytoplasmic and membrane proteins. The regional spatial shift to the cell membrane and the more significant changes of the correlated motion suggest the existence of the membrane-involved influence on the local chromosomal segments in the membrane protein expression, and it can be a key factor to segregate the whole bacterial chromosome.