Detection of Local Protein Structures along DNA Using Solid-State Nanopores

Nanopores have been successfully employed as a new tool to rapidly detect single biopolymers, in particular DNA. When a molecule is driven through a nanopore by an externally applied electric field, it causes a characteristic temporary change in the trans-pore current. Here, we examine the translocation of DNA with discrete patches of the DNA-repair protein RecA attached along its length. Using the fact that RecA-coated DNA and bare DNA yield very different current-blockade signatures, we demonstrate that it is possible to map the locations of the proteins along the length of a single molecule using a solid-state nanopore. This is achieved at high speed and without any staining. We currently obtain a spatial resolution of about 8 nm, or 5 RecA proteins binding to 15 base pairs of DNA, and we discuss possible extensions to single protein resolution. The results are a crucial first step toward genomic screening, as they demonstrate the feasibility of reading off information along DNA at high resolution with a solid-state nanopore.