Transcription elongation complex: structure and function

Our understanding of the mechanisms of transcription has been greatly advan ced by recent determination of the X-ray structure of bacterial RNA polymer ase. Using crosslinking approaches, extensive mapping of DNA and RNA contac ts onto this structure allowed tracking of the path of nucleic acids throug h the transcription elongation complex. The resulting structural model of t he transcription elongation complex is linked to the functional one, which is based on numerous data accumulated during previous studies of RNA synthe sis. An integrated structure-function model allows the rational explanation of termination and pausing and provides new insights into the mechanisms o f transcription.