p53 pulse modulation differentially regulates target gene promoters to regulate cell fate decisions.

The p53 tumor suppressor regulates distinct responses to cellular stresses. Although different stresses generate different p53 dynamics, the mechanisms by which cells decode p53 dynamics to differentially regulate target genes are not well understood. Here, we determined in individual cells how canonical p53 target gene promoters vary in responsiveness to features of p53 dynamics.

Determining the Limitations and Benefits of Noise in Gene Regulation and Signal Transduction through Single Cell, Microscopy-Based Analysis.

Stochastic fluctuations, termed "noise," in the level of biological molecules can greatly impact cellular functions. While biological noise can sometimes be detrimental, recent studies have provided an increasing number of examples in which biological noise can be functionally beneficial. Rather than provide an exhaustive review of the growing literature in this field, in this review, we focus on single-cell studies based on quantitative microscopy that have generated a deeper understanding of the sources, characteristics, limitations, and benefits of biological noise.

Transcriptional regulation improves the throughput of three-hybrid counter selections in Saccharomyces cerevisiae.

The yeast three-hybrid (Y3H) assay expands the fields of drug discovery and protein engineering by enabling the search of large variant libraries for targets that do not inherently produce a distinct, measurable phenotype. The Y3H assay links the DNA-binding and activation domains of a transcription factor via a chemically synthesized heterodimeric small molecule, thereby activating a downstream reporter gene. Although the Y3H assay has been successfully applied as a positive selection to discover novel drug targets and to evolve proteins with improved functions, its expansion into applications requiring a high-throughput, versatile selection against transcriptional activation has been hindered by its limited dynamic range as a counter selection.

Practical asymmetric synthesis of β-hydroxy γ-amino acids via complimentary aldol reactions.

Orthogonally protected chiral β-hydroxy-γ-amino acids can be accessed in >100 g quantities from readily available starting materials and reagents in 3-4 steps. These chiral synthons contain two adjacent stereocenters along with suitably protected functional groups (O-TBS, N-Boc) for downstream reactivity. Implementation of two existing aldol technologies allows rapid access to all possible stereoisomers of 1.