In addition, it regulates its synthesis as well as the production of RNAIII transcript from the agr locus. Apparently, SarA controls the transcription of the genes by binding to their respective promoters. The DNA binding activity of SarA was demonstrated to be influenced by its phosphorylation-dephosphorylation status. The redox state and pH of the Tubacin buffer were also reported to have effects on its DNA binding affinity. Interestingly, SarA also regulates the gene expression at the post-transcriptional level as its binding to various mRNA species altered their stability and turnover. SarA is highly abundant in S. aureus and even showed binding to the att site of phage ��. In solution, this global regulator exists as a dimer and is predominantly ��-helical. The X-ray crystal structure of SarA revealed it to be a winged-helix DNA binding protein harbouring two globular monomers. Each SarA monomer displays multiple ��-helices, ��- strands and loops. The putative DNA binding region of SarA is composed of a helix-turn-helix motif and a hairpin, which possibly bind to the major and minor grooves of DNA, respectively. Dimerization of SarA occurs by an N-terminal end ��-helix that is not involved in the HTH motif formation. A nascent polypeptide becomes biologically active once it is folded properly in the cell. To understand the protein folding mechanism, synthesis of the folding intermediate, and the conformational stability, unfolding of numerous proteins have been investigated in the last ~40 years using one or more denaturants and sensitive probes. Apparently, proteins are unfolded either by a two-state mechanism or by a three- or higher-state mechanism via the synthesis of one or more intermediates. In addition to providing clues on the folding mechanism and stability of proteins, unfolding data are also found to be useful in diverse biotechnological fields including drug discovery. The C-terminal halves of SarA and the related proteins are composed of the amino acid residues with comparatively higher crystallographic B-values. As the higher crystallographic B-value indicates the SAR131675 increased flexibility in protein, the C-terminal ends of Sar proteins may be more flexible than their N-terminal ends. The C-terminal ends of most Sar proteins also appeared to possess higher fraction of surface-accessible amino acid residues. Thus far, no biochemical study has been carried out to verify the flexibility/ domain structure of Sar proteins and their surface-exposed residues.