Human lysosomal DNase IIα contains two requisite PLD‐signature (HxK) motifs: Evidence for a pseudodimeric structure of the active enzyme species

Abstract

Lysosomal DNase IIα is essential for DNA waste removal and auxiliary apoptotic DNA fragmentation in higher eukaryotes. Despite the key role of this enzyme, little is known about its structure–function relationships. Here, mutational and biochemical analyses were used to characterize human DNase IIα variants expressed in mammalian cells. The resulting data strongly support the hypothesis that the enzyme is a monomeric phospholipase D–family member with a pseudodimeric protein fold. According to our results, DNase IIα contains two requisite PLD‐signature motifs ( 113 HTK 115 and 295 HSK 297 ) in the N‐ and C‐terminal subdomains, respectively, that together form a single active site. Based on these data, we present an experimentally validated structural model of DNase IIα.