The Absence of the “GATC - Binding Protein SeqA” Affects DNA Replication in Salmonella enterica Serovar Typhimurium

Abstract

The aim of this chapter is to show the consequences of seqA gene disruption in Salmonella typhimurium. Of special interest is the observation that this disruption causes asynchrony of DNA replication. In fact, lack of SeqA protein causes major changes in the lipid profile of the membrane cell which is implicated in the initiation of DNA replication. Moreover, during passage through the small intestine in the host, Salmonella typhimurium faces periodic release of bile and due to the absence of SeqA protein the sensitivity to this bile increases. This unknown sensitivity could be due to an altered membrane composition of phospholipids and fatty acids. Deoxyribonucleic acid (DNA) contains all the information required to build the cells and tissues of a prokaryotic or an eukaryotic organism. The exact replication of this information in any species assures its genetic continuity from generation to generation and is critical to the normal development of an individual. The information stored in DNA is arranged in hereditary units, known as genes, that control identifiable traits of an organism. Discovery of the structure of DNA and subsequent elucidation of how DNA directs synthesis of RNA, which then directs assembly of proteins-the so-called central dogma-were monumental achievements marking the early days of molecular biology. However, the simplified representation of the central dogma as DNA→RNA→protein does not reflect the role of proteins in the synthesis of nucleic acids. Moreover, proteins are largely responsible for regulating DNA replication and gene expression, the entire process whereby the information encoded in DNA is decoded into the proteins that characterize various cell types. One of these proteins is the DNA-Binding Protein SeqA.