| First Author | Pulugulla SH | Year | 2018 |
| Journal | J Biol Chem | Volume | 293 |
| Issue | 52 | Pages | 19942-19956 |
| PubMed ID | 30355733 | Mgi Jnum | J:302468 |
| Mgi Id | MGI:6508515 | Doi | 10.1074/jbc.RA118.005627 |
| Citation | Pulugulla SH, et al. (2018) A combined computational and experimental approach reveals the structure of a C/EBPbeta-Spi1 interaction required for IL1B gene transcription. J Biol Chem 293(52):19942-19956 |
| abstractText | We previously reported that transcription of the human IL1B gene, encoding the proinflammatory cytokine interleukin 1beta, depends on long-distance chromatin looping that is stabilized by a mutual interaction between the DNA-binding domains (DBDs) of two transcription factors: Spi1 proto-oncogene at the promoter and CCAAT enhancer-binding protein (C/EBPbeta) at a far-upstream enhancer. We have also reported that the C-terminal tail sequence beyond the C/EBPbeta leucine zipper is critical for its association with Spi1 via an exposed residue (Arg-232) located within a pocket at one end of the Spi1 DNA-recognition helix. Here, combining in vitro interaction studies with computational docking and molecular dynamics of existing X-ray structures for the Spi1 and C/EBPbeta DBDs, along with the C/EBPbeta C-terminal tail sequence, we found that the tail sequence is intimately associated with Arg-232 of Spi1. The Arg-232 pocket was computationally screened for small-molecule binding aimed at IL1B transcription inhibition, yielding l-arginine, a known anti-inflammatory amino acid, revealing a potential for disrupting the C/EBPbeta-Spi1 interaction. As evaluated by ChIP, cultured lipopolysaccharide (LPS)-activated THP-1 cells incubated with l-arginine had significantly decreased IL1B transcription and reduced C/EBPbeta's association with Spi1 on the IL1B promoter. No significant change was observed in direct binding of either Spi1 or C/EBPbeta to cognate DNA and in transcription of the C/EBPbeta-dependent IL6 gene in the same cells. These results support the notion that disordered sequences extending from a leucine zipper can mediate protein-protein interactions and can serve as druggable targets for regulating gene promoter activity. |
