The mycobacterial antibiotic resistance determinant WhiB7 acts as a transcriptional activator by binding the primary sigma factor SigA (RpoV).

Tuberculosis therapeutic options are limited by the high intrinsic antibiotic resistance of Mycobacterium tuberculosis. The putative transcriptional regulator WhiB7 is crucial for the activation of systems that provide resistance to diverse antibiotic classes. Here, we used in vitro run-off, two-hybrid assays, as well as mutagenic, complementation and protein pull-down experiments, to characterize WhiB7 as an auto-regulatory, redox-sensitive transcriptional activator in Mycobacterium smegmatis.

Separate mechanisms are involved in rifampicin upmodulated and downmodulated gene expression in Salmonella Typhimurium.

Sub-MIC antibiotics differentially modulate transcription of subsets of genes by unknown mechanisms. Paradoxically, the RNA polymerase inhibitor rifampicin is able to both upmodulate as well as downmodulate transcription when present at sub-MIC levels. In this study, we analyzed DNA sequences required for transcription modulation.

The GtaR protein negatively regulates transcription of the gtaRI operon and modulates gene transfer agent (RcGTA) expression in Rhodobacter capsulatus.

The gtaI gene of Rhodobacter capsulatus encodes an N-acyl-homoserine lactone (acyl-HSL) synthase. Immediately 5' of the gtaI gene is ORF rcc00328 that encodes a potential acyl-HSL receptor protein. A combination of genetic and biochemical approaches showed that rcc00328 (renamed gtaR) modulates the production of a genetic exchange element called the gene transfer agent (RcGTA), and regulates the transcription of gtaI.

Using invention to change how students tackle problems.

Invention activities challenge students to tackle problems that superficially appear unrelated to the course material but illustrate underlying fundamental concepts that are fundamental to material that will be presented. During our invention activities in a first-year biology class, students were presented with problems that are parallel to those that living cells must solve, in weekly sessions over a 13-wk term. We compared students who participated in the invention activities sessions with students who participated in sessions of structured problem solving and with students who did not participate in either activity.

Determinants of RasC specificity during Dictyostelium aggregation.

RasC is required for optimum activation of adenylyl cyclase A and for aggregate stream formation during the early differentiation of Dictyostelium discoideum. RasG is unable to substitute for this requirement despite its sequence similarity to RasC. A critical question is which amino acids in RasC are required for its specific function.