Direct observation of processive exoribonuclease motion using optical tweezers.

Bacterial RNases catalyze the turnover of RNA and are essential for gene expression and quality surveillance of transcripts. In Escherichia coli, the exoribonucleases RNase R and polynucleotide phosphorylase (PNPase) play critical roles in degrading RNA. Here, we developed an optical-trapping assay to monitor the translocation of individual enzymes along RNA-based substrates.

Binding and translocation of termination factor rho studied at the single-molecule level.

Rho termination factor is an essential hexameric helicase responsible for terminating 20-50% of all mRNA synthesis in Escherichia coli. We used single-molecule force spectroscopy to investigate Rho-RNA binding interactions at the Rho utilization site of the λtR1 terminator. Our results are consistent with Rho complexes adopting two states: one that binds 57 ± 2nt of RNA across all six of the Rho primary binding sites, and another that binds 85 ± 2nt at the six primary sites plus a single secondary site situated at the center of the hexamer.

The crystal structure of the Escherichia coli RNase E apoprotein and a mechanism for RNA degradation.

RNase E is an essential bacterial endoribonuclease involved in the turnover of messenger RNA and the maturation of structured RNA precursors in Escherichia coli. Here, we present the crystal structure of the E. coli RNase E catalytic domain in the apo-state at 3.

Regulation of lifespan in Drosophila by modulation of genes in the TOR signaling pathway.

In many species, reducing nutrient intake without causing malnutrition extends lifespan. Like DR (dietary restriction), modulation of genes in the insulin-signaling pathway, known to alter nutrient sensing, has been shown to extend lifespan in various species. In Drosophila, the target of rapamycin (TOR) and the insulin pathways have emerged as major regulators of growth and size.