Nucleoid-associated proteins (NAPs) in prokaryotes play an important architectural role in DNA bending, supercoiling and DNA compaction. In addition to architectural roles, some NAPs also play regulatory roles in DNA replication and repair, and act as global transcriptional regulators in many bacteria. Bacteria encode multiple NAPs and some of them are even essential for survival. Streptococcus mutans, a dental pathogen, encodes one such essential NAP called histone-like protein (HLP). Here, the three-dimensional structure of S. mutans HLP has been determined to 1.9 Å resolution. The HLP structure is a dimer and shares a high degree of similarity with other bacterial NAPs, including HU. Since HLPs are essential for the survival of pathogenic streptococci, this structure determination is potentially beneficial for future drug development against these pathogens.
Keywords: HLP; Streptococcus mutans; histone-like protein; nucleoid-associated protein.