A new pipeline SPICE identifies novel JUN-IKZF1 composite elements

Transcription factor partners can cooperatively bind to DNA composite elements to augment gene transcription. Here, we report a novel protein-DNA binding screening pipeline, termed Spacing Preference Identification of Composite Elements (SPICE), that can systematically predict protein binding partners and DNA motif spacing preferences. SPICE de novo predicted known composite elements, including AP1-IRF composite elements (AICE) and STAT5 tetramers, and also predicted a range of novel binding partners, including JUN-IKZF1 composite elements, including at an upstream conserved noncoding region, CNS9, in the human IL10 gene, which contains a non-canonical IKZF1 site. We confirmed cooperative binding of JUN and IKZF1 and showed that the activity of an IL10 -luciferase reporter construct in primary B and T cells depended on both this site and the AP1 binding site within this composite element. Overall, our findings reveal an unappreciated global association of IKZF1 and AP1 and establish SPICE as a valuable new pipeline for predicting novel transcription binding complexes. ### Competing Interest Statement The authors have declared no competing interest.