End of the Beginning: Elongation and Termination Features of Alternative Modes of Chromosomal Replication Initiation in Bacteria

摘要: In bacterial cells, bidirectional replication of the circular chromosome is initiated from a single origin (oriC) and terminates in an antipodal terminus region such that movement pair forks largely codirectional with transcription. The flanked by discrete Ter sequences act as polar, or direction-dependent, arrest sites for fork progression. Alternative oriC-independent modes initiation are possible, one which constitutive stable DNA (cSDR) transcription-associated RNA-DNA hybrids R-loops. Here, I discuss distinctive attributes progression termination associated different initiation. Two hypothetical models proposed: head-on collisions between pairs forks, feature all kingdoms life, provoke bilateral reversal reactions; cSDR characterized existence distinct subpopulations cultures widespread distribution origins genome, each small firing potential. Since R-loops known to exist eukaryotic cells inflict genome damage G1 phase, it possible cSDR-like events promote aberrant even eukaryotes.