ATACsequencing

ATAC-seq, which stands for Assay for Transposase-Accessible Chromatin using sequencing, is a molecular biology technique used to study the accessibility of chromatin. Chromatin is the complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells. The accessibility of chromatin is a key determinant of gene expression, as it dictates whether transcription factors and other regulatory proteins can bind to the DNA. ATAC-seq specifically identifies regions of open chromatin.

The technique works by using a hyperactive transposase enzyme, commonly derived from the bacterium *Bacteroides fragilis*. This transposase enzyme is engineered to bind to and cut DNA in open, accessible regions of chromatin. It simultaneously inserts short DNA adapters into these cut sites. Following the transposase reaction, the DNA fragments with the inserted adapters are isolated and then amplified using polymerase chain reaction (PCR). Finally, these amplified fragments are sequenced using high-throughput sequencing technologies.

The resulting sequence reads can be mapped back to a reference genome to identify the genomic locations where the DNA was accessible. This information provides a genome-wide profile of open chromatin, which is often correlated with active gene regulatory elements such as enhancers and promoters. ATAC-seq is a powerful tool for understanding gene regulation, cell differentiation, and the epigenetic changes that occur in various biological states, including disease. It is known for its efficiency and low cell input requirements compared to older chromatin accessibility assays.