Fig. 4

PIAS1 SUMOylates SAMHD1 at K469, K595, and K622. A The schematic representation of SAMHD1 protein (1–626). The three SUMOylation consensus motifs were labeled as indicated. NLS nuclear localization signal, SAM sterile alpha motif, HD domain histidine and aspartic acid domain, V vpx interacting motif; T592: phosphorylation site mediated by cellular CDK1/2 and the conserved herpesvirus protein kinases. B In vitro SUMOylation assay was performed with the combination of E1, E2, SUMO2, PIAS1, and WT or individual SAMHD1 mutant [K469R, K595R, K622R, or RRR(K469R/K595R/K622R)] as indicated. The reaction was terminated with SDS sample loading buffer and WB was performed using anti-SAMHD1. Arrows denote mono- or di-SUMOylated SAMHD1. C The localization of K469 and K595 in SAMHD1 tetramer. The SAMHD1 tetramer structure (PDB# 4TNZ) was used to locate K469 and K595 using Chimera software. D The localization of K469, K595 and K622 in full-length SAMHD1 monomer. The SAMHD1 structure was predicted using I-TASSER algorithm and localization of K469, K595 and K622 was labeled using Chimera software