[Lsr2: A Nucleoid Associated Protein (NAP) and a transcription factor in mycobacteria]

Lsr2, a small protein mainly found in actinobacteria, plays a crucial role in the virulence and adaptation of mycobacteria to environmental conditions. As a member of the nucleoid-associated protein (NAPs) superfamily, Lsr2 influences DNA organization by facilitating the formation of chromosomal loops in vitro and, therefore, may be a major player in the three-dimensional folding of the genome. Additionally, Lsr2 also acts as a transcription factor, regulating the expression of numerous genes responsible for coordinating a myriad of cellular and molecular processes essential for the actinobacteria. Similar to the H-NS protein, its ortholog in enterobacteria, its role in transcriptional repression likely relies on oligomerization, rigidifying, and bridging of DNA, thereby disrupting RNA polymerase recruitment as well as the elongation of RNA transcripts.