Question

Genomic methods and thinking about what their results might mean. One of the first genomic methods to study nuclear organization genome-wide was DamID, which was first carried out using lamin B1 DamID.

i.  Explain how the DamID method works

Answer 1

Ans .The DNA adenine methyltransferase identification (DamID) assay is a powerful method to detect protein-DNA interactions both locally and genome-wide. It is an alternative approach to chromatin immunoprecipitation (ChIP).

The original Lamin B1-DamID gets around this by fusing the insoluble nuclear Lamina B1 protein with a bacterial Dam methylase.

DamID identifies binding sites by expressing the proposed DNA-binding protein as a fusion protein with DNA methyltransferase. Binding of protein of interest to DNA localizes the methyltransferase in the region of binding site.

Targeted DamID approach uses of phenomena of ribosome reinitiation to express Dam-fusion proteins at appropriately low levels for DamID. This construct can be combined with cell-type specific promoters resulting in tissue-specific methylation.This approach can be used to assay transcription factor binding in a cell type of interest or alternatively, dam can be fused to Pol II subunits to determine binding of RNA polymerase and thus infer cell-specific gene expression.