Mechanisms and Controls of DNA Replication in Bacteria

Abstract

DNA is the polymeric molecule that contains all the genetic information in a cell. This genetic information encodes the instructions to make a copy of itself, for the cellular structure, for the operative cellular machinery and also contains the regulatory signals, which determine when parts of this machinery should be on or off. The operative machinery in turn, is responsible for the cells functions either metabolically or in interactions with the environment. Part of this cellular machinery devoted to DNA metabolism is responsible for DNA replication, DNA-repair and for the regulation of gene expression. In this chapter we will focus our discussion on the mechanisms and controls that conduct DNA replication in bacteria, including the components, functions and regulation of replication machinery. Most of our discourse will consider this biological process in Escherichia coli but when possible we will compare it to other bacterial models, mainly Bacillus subtilis and Caulobacter crescentus as examples of organisms with asymmetrical cell division. In order to maintain a bacterial population it is necessary that cells divide, but before the physical division of a daughter cell from its mother, it is necessary among other check points, that the DNA has been replicated accurately. This is done by the universal semiconservative replication process of DNA-strands, which generates two identical strand copies from their parent templates. To better understand this process it has been divided into three phases: initiation, elongation and termination of DNA replication. In each of these steps, multiple stable and transient interactions are involved and we have summarized them below.