Berlin 2008 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 15: Single Molecules

BP 15.5: Vortrag

Mittwoch, 27. Februar 2008, 15:00–15:15, C 243

A unified model of transcription elongation — •Dáibhid Ó Maoiléidigh — Max Planck Institute for the Physics of Complex Systems, Dresden, Germany

The copying of DNA into RNA is the first step required for the production of proteins and RNA with a direct function. This process of transcription is highly regulated and is carried out by RNA polymerase (RNAP), a complex multi-functional molecular motor. In this talk we present a model which explains most published single-molecule observations of the elongation of the RNA transcript by RNAP. The model is an extension of previous work where we successfully predicted the sequence dependent positions of pauses during the elongation process [1]. Pauses have many functions, for example, they are associated with the correction of errors during transcription and are required for the termination of transcription. We have proposed previously that the folding of the RNA transcript behind RNAP creates a barrier which restricts the backwards movement of RNAP along DNA during a pause [1]. We now provide an estimate for the barrier position distribution. Furthermore, we present new analytical expressions which describe the dependence of the elongation velocity on force applied in single-molecule experiments. The model resolves many of the inconsistencies in the interpretations of single-molecule experiments on transcription elongation and illuminates mechanisms for its control.

[1] Tadigotla V. R., Ó Maoiléidigh D., Sengupta A. M., Epshtein V., Ebright R. H., Nudler E., Ruckenstein A. E., Proc Natl Acad Sci U S A, 103:4439-44 (2006).