Comparative Purification and Characterization of Two HIN Domains, Hematopoietic Interferon-Inducible Nuclear Antigens with a 200-Amino-Acid Repeat, in Murine AIM2-Like Receptors

HIN (hematopoietic interferon-inducible nuclear antigens with a 200-amino-acid repeat) domains are found in all AIM2-like receptors (ALRs) and mediate protein/DNA interactions to regulate innate immunity. We cloned, expressed, and purified the human interferon-inducible protein p202 (111202) HINb domain and the murine 111203 HIN domain using Escherichia coli JM109 (DE3) host cells. The Ifi203 HIN domain is a monomer in solution, and it has the ability to bind both double-stranded DNA and RNA. In contrast, the Ifi202 HINb domain is a dimer in solution, and no interaction with double-stranded DNA or RNA was detected. A complex of the Ifi203 HIN domain and double-stranded DNA was prepared, and crystals of the complex were obtained. To analyze further the dimeric interface of the Ifi202 HINb domain and the DNA binding site of the Ifi203 HIN domain, models of both proteins were developed. This work provides a basis for understanding the structure and function of HIN domains.