Laser crosslinking ofE.coliRNA polymerase and T7 DNA

Abstract
The first photochemical crosslinking of a protein to a nucleic acid using laser excitation is reported. A single, 120 mJ, 20 ns pulse at 248 nm crosslinks about 10% of bound E. coli RNA polymerase to T7 DNA under the conditions studied. The crosslinking yield depends on mercaptoethanol concentration, and is a linear function of laser intensity. The protein subunits crosslinked to DNA are β, β' and δ.