Nucleoid Case Study Tb

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Chapter I
General Introduction

A. Bacterial nucleoid
Bacteria lacks nucleus and other membrane bound organelles. Hence all the cellular components, including proteins, DNA, RNA and other compounds are located within inside the cytosol. The region of the cell which encompasses the bacterial genomic DNA is termed ‘Nucleoid’. Nucleoid is composed largely of DNA and small amounts of proteins and RNA (Dillon and Dorman, 2010; Dorman, 2014a; Thanbichler et al., 2005). The genomic DNA is organized for storage in ways that are compatible with all the major DNA-related processes like replication, transcription and chromosome segregation. Proteins that play important role(s) in the structuring of DNA and having the potential to influence gene expression have been explored in all kingdoms of life. The organization of bacterial chromosome is influenced by several important factors. These factors include molecular crowding (de Vries, 2010), negative supercoiling of DNA (Postow et al., 2004), the influence of NAPs (nucleoid-associated proteins) and transcription (Dillon and Dorman, 2010; Dorman, 2009, 2013b;
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tuberculosis in 1882 and showed it to be the causative agent of tuberculosis (TB). M. tuberculosis, being a member of pathogenic, slow-growing mycobacterial species, shows an average doubling time of 12-24 hours and also shows prolonged culture period of approximately 21 days on agar. M. tuberculosis is a rod-shaped bacterium, having a length of around 2-4µm and being 0.2-0.4µm wide. It is classified as an acid-fast Gram-positive bacterium, as it does not retain any bacterial stain and Ziehl-Neelson staining is used. M. tuberculosis is enveloped by the cell-wall, which is wax-rich and consists of long chain fatty acids, glycolipids and several other constituents. Around 250 genes in M. tuberculosis genome are linked to fatty-acid metabolism. This cell-wall protects M. tuberculosis and is important for its survival in host
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