Q.13 Protein-DNA interactions in vivo can be studied by
(A) gel shift assay (B) Southern hybridization
(C) chromatin immunoprecipitation assay (D) fluorescence in situ hybridization assay
Protein-DNA interactions drive gene regulation, and studying them in vivo captures native cellular contexts like chromatin states. Chromatin immunoprecipitation assay (ChIP) crosslinks and isolates these interactions directly from living cells. This method excels in biotechnology for mapping transcription factor binding sites genome-wide.
Correct Answer
Chromatin immunoprecipitation assay (C) enables in vivo analysis by fixing proteins to DNA with formaldehyde, then using specific antibodies to pull down complexes for downstream PCR or sequencing. Unlike in vitro techniques, ChIP preserves physiological conditions, revealing dynamic bindings in mammalian cell cultures or microbial systems. It supports enzyme kinetics studies by quantifying occupancy at promoters.
Option Explanations
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Gel shift assay (A): Electrophoretic mobility shift assay (EMSA) mixes purified proteins with labeled DNA probes in vitro; bound complexes migrate slower in gels, but lacks cellular context.
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Southern hybridization (B): Detects specific DNA sequences post-restriction digest via probe hybridization; analyzes DNA structure, not protein binding.
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Chromatin immunoprecipitation assay (C): Antibodies capture native protein-DNA complexes from crosslinked chromatin in vivo, ideal for epigenetics and signaling pathways.
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Fluorescence in situ hybridization assay (D): FISH visualizes DNA/RNA sequences via fluorescent probes in fixed cells; maps loci but ignores protein interactions.
Biotech Applications
ChIP integrates with next-gen sequencing (ChIP-seq) for genome-wide mapping in bioengineering projects like promoter engineering. In Jaipur-based research, it probes microbial gene regulation during fermentation, enhancing SEO-optimized publications on molecular genetics.
