New crystal structures of transcription complexes formed by bacteriophage T7 RNA polymerase reveal a nucleotide-addition cycle driven by active-site conformational changes similar to those observed in DNA polymerases, and suggest provocative hypotheses for the more complex multisubunit RNA polymerases of free-living organisms.

We describe two methods for creating long (>1 kb) dsRNA molecules with specific, user-controlled overhangs for efficient hybridization and ligation. The two methods create double-stranded RNA (dsRNA) molecules with 5' overhangs or with 3' overhangs using T7 RNA polymerase (T7 RNAP) in transcription reactions of carefully designed PCR products. Primers utilized in the PCR reactions provide the t...

Recently, we reported that DNA associated with inverse hexagonal (H(II)) lyotropic liquid crystal phases of the lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) was actively transcribed by T7 RNA polymerase. Our findings suggested that key components of the transcription process, probably the T7 RNA polymerase and the DNA, remained associated with the monolithic H(II) phase throughout...

Malondialdehyde, a genotoxic byproduct of lipid peroxidation, reacts with guanine in DNA to form pyrimido[1,2-alpha]purin-10(3H)one (M(1)dG), the first endogenous DNA lesion found to be a target of nucleotide excision repair enzymes. A subpathway of nucleotide excision repair, transcription-coupled repair, is thought to occur when RNA polymerase (RNAP) is arrested at damage in transcribed DNA s...

Transcription in human mitochondria is carried out by a single-subunit, T7-like RNA polymerase assisted by several auxiliary factors. We demonstrate that an essential initiation factor, TFB2, forms a network of interactions with DNA near the transcription start site and facilitates promoter melting but may not be essential for promoter recognition. Unexpectedly, catalytic autolabeling reveals t...

Polymerases form a class of enzymes that act as molecular motors as they move along their nucleic acid substrate during catalysis, incorporating nucleotide triphosphates at the end of the growing chain and consuming chemical energy. A debated issue is how the enzyme converts chemical energy into motion [J. Gelles and R. Landick, Cell 93, 13 (1998)]. In a single molecule assay, we studied how an...