Transcription elongation complex: structure and function.

Our understanding of the mechanisms of transcription has been greatly advanced by recent determination of the X-ray structure of bacterial RNA polymerase. Using crosslinking approaches, extensive mapping of DNA and RNA contacts onto this structure allowed tracking of the path of nucleic acids through the transcription elongation complex. The resulting structural model of the transcription elongation complex is linked to the functional one, which is based on numerous data accumulated during previous studies of RNA synthesis. An integrated structure-function model allows the rational explanation of termination and pausing and provides new insights into the mechanisms of transcription.