Enzolution™ TREX1 Assay System

The TREX1 Assay System is intended for use with the Transcreener® dAMP FP Assay Kit (#BBL-3028) to measure enzymatic activity for TREX1 (also known as Three Prime Repair Exonuclease 1). TREX1 is the major exonuclease responsible for degrading cytosolic DNA, and it plays an important role in preventing aberrant autoimmune responses in normal cells by acting as a checkpoint for the cGAS/STING pathway. It is a 3’-5’ exonuclease that cleaves single bases from the 5’ termini of double stranded or single stranded DNA, releasing deoxynucleoside monophosphates, including deoxy-AMP (dAMP). The Transcreener dAMP FP assay enables sensitive detection of dAMP in a single addition, mix-and-read format that has been optimized and extensively validated for high throughput screening (HTS) and inhibitor dose response measurements using most multimode plate readers.

The TREX1 Assay System provides all reagents required to screen and profile TREX1 inhibitors when used with the Transcreener dAMP FP Assay Kit, including purified human TREX1 (amino acids 1-286, C-terminal 6xHis) and DNA substrate. TREX1 is relatively non-specific for its DNA substrate; the TREX1 Assay System uses interferon stimulatory DNA (ISD), a 45bp dsDNA oligomer from the Listeria monocytogenes genome that induces a strong type I IFN response in mammalian cells. Note the assay has been optimized using a saturating concentration of ISD, which makes the assay relatively insensitive to DNA-competitive inhibitors; use of lower ISD concentrations will require adjustment of the TREX1 concentration accordingly. Also, the protocol is configured for 384-well plates; use of different multiwell plate formats will require some additional optimization.

The main applications for this assay system are, i) screening for TREX1 inhibitors, ii) generating dose response curves and IC50 values for TREX1 inhibitors, and iii) kinetic and mechanistic analyses.