The unit content of DNA in a living organism containing all of its genes is referred to as ‘genome’, which forms the basis oflife and heredity. In the path of evolution from a single-cellular prokaryotic life to multi-cellular eukaryotic system, thegenome has become more and more complex not only in the context of size but also in sequence and content. Although thesize of the genome does not directly correlate with the complexity and hierarchy of a living organism, in the eukaryoticsystem with restricted nuclear size, disproportionately higher size of DNA is packed into a highly ordered manner (Kumariet al., in Kundu (eds) Epigenetics: development and disease. Subcellular biochemistry, Springer, Dordrecht, 2013). Thispackaging of genome with the assistance of protein and RNA is not a unique feature of the eukaryotic system alone. In fact,even in a tiny prokaryotic cell, to reduce the volume and to restrict the signal dependent availability of the genomic material(DNA), packing of genome is essential. In this brief article, we shall try to put forward a concept of genome organizationand epigenetic machineries to assist the functional ability of the genomic material in the evolutionary perspective.

The Aurora kinases represent a group of serine/threonine kinases which are crucial regulators of mitosis. DysregulatedAurora kinase B (AurkB) expression, stemming from genomic amplification, increased gene transcription or overexpressionof its allosteric activators, is capable of initiating and sustaining malignant phenotypes. Although AurkB level in cells iswell-orchestrated, studies that relate to its stability or activity, independent of mitosis, are lacking. We report that AurkBundergoes acetylation in vitro by lysine acetyltransferases (KATs) belonging to different families, namely by p300 andTip60. The haploinsufficient tumor suppressor Tip60 acetylates two highly conserved lysine residues within the kinasedomain of AurkB which not only impinges the protein stability but also its kinase activity. These results signify a probableoutcome on the increase in ‘‘overall activity’’ of AurkB upon Tip60 downregulation, as observed under cancerous conditions.The present work, therefore, uncovers an important functional interplay between AurkB and Tip60, frailty of whichmay be an initial event in carcinogenesis.

Besides the fundamental components of the chromatin, DNA and octameric histone, the non-histone chromatinproteins and non-coding RNA play a critical role in the organization of functional chromatin domains. Thenon-histone chromatin proteins therefore regulate the transcriptional outcome in both physiological andpathophysiological state as well. They also help to maintain the epigenetic state of the genome indirectly.Several transcription factors and histone interacting factors also contribute in the maintenance of the epigeneticstates, especially acetylation by the induction of autoacetylation ability of p300/CBP. Alterations of KATactivity have been found to be causally related to disease manifestation, and thus could be potential therapeutictarget.