Recombinant expression, purification, and crystallization of the sterile α-motif/histidine-aspartate domain-containing protein from chicken

- For the first time, chicken SAMHD1 (101-614) was expressed in an E. coli system.
- Chicken SAMHD1 (101-614) was firstly found to possess dNTPase activities in vitro, which suggested that it could be a potential antiviral factor against avian viruses.
- We purified the protein of Chicken SAMHD1 (101-614) and obtained the crystals.

The sterile α-motif and HD domain containing protein 1 (SAMHD1) family is a newly identified protein family, involved in innate immunity restriction. This family possesses a broad-spectrum of antiviral activity. The SAMHD1 family in chicken has not been clearly documented. Here, we expressed chicken SAMHD1 (101-614) fused with a SUMO tag in an Escherichia coli (E. coli) system. For the first time, chicken SAMHD1 (101-614) was found to possess dNTPase cleavage activities in vitro. This suggests that chicken SAMHD1 may be a potential antiviral factor against avian viruses. Through a unique purification method, the purity of the protein as estimated by SDS-PAGE was >95% after a double Ni affinity chromatography and gel filtration purification. Using a sitting-drop vapor-diffusion method, protein crystals were obtained. This study provides some essential method and information for further structure and function determinations of chicken SAMHD1.