Structural features of Dnase1L3 responsible for serum antigen clearance

Abstract

Autoimmunity develops when extracellular DNA released from dying cells is not cleared from serum. While serum DNA is primarily digested by Dnase1 and Dnase1L3, Dnase1 does not rescue autoimmunity arising from Dnase1L3 deficiencies. Dnase1L3 uniquely degrades antigenic forms of cell-free DNA, including DNA complexed with lipids and proteins. The distinct activity of Dnase1L3 relies on its unique C-terminal Domain (CTD), but the mechanism is unknown. We used multiple biophysical techniques and functional assays to study the interplay between the core catalytic domain and the CTD. While the core domain resembles Dnase1, there are several key differences between the two enzymes. Dnase1L3 is not inhibited by actin due to multiple differences in the actin recognition site. The CTD augments the ability of the core to bind DNA, thereby facilitating the degradation of complexed DNA to prevent autoimmune pathology. Together, these structural insights will inform the development of Dnase1L3-based therapies for autoimmunity.

Origin and significance of the human DNase repertoire

“…S2 d). Experimental evidence of disulfide bond formation comes from DNase1 crystallographic structures 35 , 36 and from a very recent crystal structure of DNase1L3 37 . Of the three recognizable cysteine pairs, C4-C32 is found exclusively in DNase1L1, DNase1L1L, and DNase1L3 (Supplementary Fig.…”

Origin and significance of the human DNase repertoire

“…S2d). Experimental evidence of disul de bond formation comes from DNase1 crystallographic structures 33,34 and from a very recent crystal structure of DNase1L3 35 . Of the three recognizable cysteine pairs, C4-C32 is found exclusively in DNase1L1, DNase1L1L, and DNase1L3 (Supplementary Fig.…”