Showing papers by "Robert A. Weisberg published in 2003"
TL;DR: Nascent transcripts of the phage HK022 put sites modify the transcription elongation complex so that it terminates less efficiently at intrinsic transcription terminators and accelerates through pause sites, suggesting that put inhibits a step that is common to termination at the different types of terminator.
Abstract: Nascent transcripts of the phage HK022 put sites modify the transcription elongation complex so that it terminates less efficiently at intrinsic transcription terminators and accelerates through pause sites. We show here that the modification also suppresses termination in vivo at two factor-dependent terminators, one that depends on the bacterial Rho protein and a second that depends on the HK022-encoded Nun protein. Suppression was efficient when the termination factors were present at physiological levels, but an increase in the intracellular concentration of Nun increased termination both in the presence and absence of put. put-mediated antitermination thus shows no apparent terminator specificity, suggesting that put inhibits a step that is common to termination at the different types of terminator.
13 citations
TL;DR: It is proposed that insertion into secondary sites is a step in the evolutionary change of phage insertion specificity and a model of how this might occur is presented and accounts for the unexpected segregation pattern of the overlap region observed after insertion into several secondary sites.
13 citations
TL;DR: The chapter discusses the mode of action of the repressor-operator complex on the transcription elongation complex (TEC) and effect of a lac repressor roadblock on expression of a downstream gene in vivo and transcription in vitro.
Abstract: Publisher Summary The Escherichia coli (E. coli) Lac repressor is one of the best characterized sequence specific DNA binding proteins. The chapter discusses the mode of action of the repressor-operator complex on the transcription elongation complex (TEC) analyzed lac operon transcripts in vivo and transcripts generated from operator containing constructs in vivo and in vitro. Several studies have shown that the lac repressor is a versatile transcriptional roadblock in vivo and in vitro. Roadblocked TECs remain active and can be probed by a number of physical, chemical, and enzymatic methods. The exact state of the halted TECs depends on the sequences in the vicinity of the halt site. The chapter discusses effect of a lac repressor roadblock on expression of a downstream gene in vivo and transcription in vitro. The protocol for roadblocking the TEC with lac repressor is given.
12 citations