Since 1988, I have been conducting biochemical and genetic studies of the mechanisms regulatingtranscription elongation and termination in prokaryotes and eukaryotes using E. coli and yeast S.cerevisiae as model systems. My laboratory is responsible for several key findings that substantiallyadvanced our knowledge of transcription regulation at post-initiation level. These findings include: (1)Discovery of the novel mechanism for regulation of transcription elongation and promoter escape (broadly know as RNA polymerase backtracking), (2) elucidation of the mechanisms governing transcription by RNA polymerase II through the nucleosomes and identification of transcription factors assisting the process, (3) development of an in vitro transcription system (known as promoter-independent reconstitution of transcription elongation complexes) for the analysis of transcription elongation mechanisms, (4) determination of several principal mechanisms of transcription pausing by bacterial and yeast RNA polymerases, (5) elucidation of the mechanism enabling RNA polymerase to transcribe UV-damaged DNA and the mechanism for initiation of transcription-coupled DNA repair (TCR), (6) molecular dissection of the mechanism of intrinsic transcription termination in bacteria, (7) determination of several mechanism controlling transcription fidelity by RNA polymerase II. My current research involves biochemical and genetic analysis of the mechanisms of transcription fidelity and impact of transcription errors to cell physiology, aging, and cancer, role of RNA polymerase in transcription coupled DNA repair, molecular mechanisms of transcription by RNA polymerase II in context of chromatin and mechanisms of transcription termination and antitermination in bacteria.