title: Collision events between RNA polymerases in convergent transcription studied by atomic force microscopy.
abstract: Atomic force microscopy (AFM) has been used to image, at single molecule resolution, transcription events by Escherichia coli RNA polymerase (RNAP) on a linear DNA template with two convergently aligned lambda(pr) promoters. For the first time experimentally, the outcome of collision events during convergent transcription by two identical RNAP has been studied. Measurement of the positions of the RNAP on the DNA, allows distinction of open promoter complexes (OPCs) and elongating complexes (EC) and collided complexes (CC). This discontinuous time-course enables subsequent analysis of collision events where both RNAP remain bound on the DNA. After collision, the elongating RNAP has caused the other (usually stalled) RNAP to back-track along the template. The final positions of the two RNAP indicate that these are collisions between an EC and a stalled EC (SEC) or OPC (previously referred to as sitting-ducks). Interestingly, the distances between the two RNAP show that they are not always at closest approach after 'collision' has caused their arrest.
authors.affiliation: Department of Oral Biology, University of Leeds, Leeds LS2 9LU, UK.
authors.forename: Neal
authors.initials: N
authors.lastname: Crampton
authors.forename: William A
authors.initials: WA
authors.lastname: Bonass
authors.forename: Jennifer
authors.initials: J
authors.lastname: Kirkham
authors.forename: Claudio
authors.initials: C
authors.lastname: Rivetti
authors.forename: Neil H
authors.initials: NH
authors.lastname: Thomson
mesh_terms: D004247:DNA / Q000737:chemistry / Q000648:ultrastructure*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism / Q000648:ultrastructure*; D004926:Escherichia coli / Q000201:enzymology; D018625:Microscopy, Atomic Force; D008957:Models, Genetic; D013698:Templates, Genetic; D014158:Transcription, Genetic
chemical_list: D004247:DNA; D012321:DNA-Directed RNA Polymerases