Static and Kinetic Site-Specific ProteinDNA Photocrosslinking: Analysis of Bacterial Transcription Initiation Complexes

Static site-specific protein–DNA photocrosslinking permits identification of protein–DNA interactions within multiprotein–DNA complexes. Kinetic site-specific protein–DNA photocrosslinking – involving rapid-quench-flow mixing and pulsed-laser irradiation – permits elucidation of pathways and kinetics of formation of protein–DNA interactions within multiprotein–DNA complexes. We present detailed protocols for application of static and kinetic site-specific protein–DNA photocrosslinking to bacterial transcription initiation complexes.