Low Signal from Using N-ChIP for Weak DNA-Binding Proteins

Symptom

Consistently low or absent signal when studying transcription factors or chromatin-associated proteins using native ChIP (N-ChIP). Histone ChIP experiments work well in the same laboratory.

1. 1 Target proteins have weak DNA affinity and dissociate during N-ChIP
2. 2 Proteins located far from DNA require cross-linking for stabilization
3. 3 N-ChIP suitable only for tightly associated proteins like histones
4. 4 Lack of formaldehyde cross-linking allows protein-DNA complex dissociation

1. 1 Use X-ChIP (cross-linked ChIP) for proteins with weaker DNA affinity
2. 2 Use X-ChIP for proteins located far from DNA (e.g. chromatin remodelers)
3. 3 Cross-link with 1% formaldehyde for 10-15 min before cell lysis
4. 4 Reserve N-ChIP exclusively for histones and very tightly bound proteins

Related Video (2)

JoVE (Open Access) ★ 78

Automating ChIP-seq Experiments to Generate Epigenetic Profiles on 10,000 HeLa Cells

"Automated ChIP-seq protocol on low cell numbers directly parallels the N-ChIP weak signal issue and offers a modern workflow alternative for hard-to-detect chromatin proteins."

JoVE (Open Access) ★ 70

Discovering CsgD Regulatory Targets in Salmonella Biofilm Using Chromatin Immunoprecipitation and High-Throughput Sequencing (ChIP-seq)

"Demonstrates ChIP-seq for discovering transcription factor regulatory targets, the exact experimental context where weak DNA-binding protein signal fails in N-ChIP."