Supplementary Figure 5: Generation and characterization of Bhlhe41^Tag/Tag mice.

(a) Schematic domain structure (not drawn to scale) of the tagged Bhlhe41 protein that is expressed from the Bhlhe41^Tag allele. The tag sequences added at the last codon of Bhlhe41 contained epitopes for Flag and V5 antibodies, two cleavage sites for the TEV protease and a biotin acceptor sequence for biotinylation by the Escherichia coli biotin ligase BirA. (b) Frequency of peritoneal and splenic B-1a cells in wild-type and Bhlhe41^Tag/Tag mice. Three mice of each genotype were analyzed. Horizontal bars indicate mean value, and error bars represent s.d. (c) Gene set enrichment analysis (GSEA). The Bhlhe41/Bhlhe40-repressed genes identified in V_H12/Vκ4 transgenic B-1a cells were compared to the ranked log2-fold gene expression changes between polyclonal DKO and wild-type B-1a cells (left). Likewise, the Bhlhe41/Bhlhe40-repressed genes identified in polyclonal B-1a cells were compared to the ranked log2-fold gene expression changes between V_H12/Vκ4 transgenic DKO and wild-type B-1a cells (right). (d) The average density of open chromatin (determined by ATAC-seq) at all genomic Bhlhe41 peaks (left) or at the 117 Bhlhe41 peaks present at repressed target genes was assessed for a region extending from -1 kb to +1 kb relative to the Bhlhe41 peak summit.