Efficient modification of λ-DNA substrates for single-molecule studies.

Single-molecule studies of protein-nucleic acid interactions frequently require site-specific modification of long DNA substrates. The bacteriophage λ is a convenient source of high quality long (48.5 kb) DNA.

Regulation of the transcriptional activator NtrC1: structural studies of the regulatory and AAA+ ATPase domains.

Transcription by sigma54 RNA polymerase depends on activators that contain ATPase domains of the AAA+ class. These activators, which are often response regulators of two-component signal transduction systems, remodel the polymerase so that it can form open complexes at promoters. Here, we report the first crystal structures of the ATPase domain of an activator, the NtrC1 protein from the extreme thermophile Aquifex aeolicus.