Bacteriophage λ RexA and RexB functions assist the transition from lysogeny to lytic growth.

The CI and Cro repressors of bacteriophage λ create a bistable switch between lysogenic and lytic growth. In λ lysogens, CI repressor expressed from the P promoter blocks expression of the lytic promoters P and P to allow stable maintenance of the lysogenic state. When lysogens are induced, CI repressor is inactivated and Cro repressor is expressed from the lytic P promoter.

Elements in the λ immunity region regulate phage development: beyond the 'Genetic Switch'.

Genetic elements in the bacteriophage λ immunity region contribute to stable maintenance and synchronous induction of the integrated Escherichia coli prophage. There is a bistable switch between lysogenic and lytic growth that is orchestrated by the CI and Cro repressors acting on the lytic (P and P ) and lysogenic (P ) promoters, referred to as the Genetic Switch. Other less well-characterized elements in the phage immunity region include the P promoter and the immunity terminator, T .

A Transcription Fidelity Reporter Identifies GreA as a Major RNA Proofreading Factor in .

We made a coupled genetic reporter that detects rare transcription misincorporation errors to measure RNA polymerase transcription fidelity in Using this reporter, we demonstrated that the transcript cleavage factor GreA, but not GreB, is essential for proofreading of a transcription error where a riboA has been misincorporated instead of a riboG. A mutant strain had more than a 100-fold increase in transcription errors relative to wild-type or a mutant. However, overexpression of GreB in Δ cells reduced the misincorporation errors to wild-type levels, demonstrating that GreB at high concentration could substitute for GreA in RNA proofreading activity .

Bacteriophage λ N protein inhibits transcription slippage by Escherichia coli RNA polymerase.

Transcriptional slippage is a class of error in which ribonucleic acid (RNA) polymerase incorporates nucleotides out of register, with respect to the deoxyribonucleic acid (DNA) template. This phenomenon is involved in gene regulation mechanisms and in the development of diverse diseases. The bacteriophage λ N protein reduces transcriptional slippage within actively growing cells and in vitro.

Isolation and characterization of RNA polymerase rpoB mutations that alter transcription slippage during elongation in Escherichia coli.

Transcription fidelity is critical for maintaining the accurate flow of genetic information. The study of transcription fidelity has been limited because the intrinsic error rate of transcription is obscured by the higher error rate of translation, making identification of phenotypes associated with transcription infidelity challenging. Slippage of elongating RNA polymerase (RNAP) on homopolymeric A/T tracts in DNA represents a special type of transcription error leading to disruption of open reading frames in Escherichia coli mRNA.

Probing cellular processes with oligo-mediated recombination and using the knowledge gained to optimize recombineering.

Recombination with single-strand DNA oligonucleotides (oligos) in Escherichia coli is an efficient and rapid way to modify replicons in vivo. The generation of nucleotide alteration by oligo recombination provides novel assays for studying cellular processes. Single-strand exonucleases inhibit oligo recombination, and recombination is increased by mutating all four known exonucleases.