A high-resolution view of RNA endonuclease cleavage in Bacillus subtilis.

RNA endonucleases are the rate-limiting initiator of decay for many bacterial mRNAs. However, the positions of cleavage and their sequence determinants remain elusive even for the well-studied Bacillus subtilis. Here we present two complementary approaches-transcriptome-wide mapping of endoribonucleolytic activity and deep mutational scanning of RNA cleavage sites-that reveal distinct rules governing the specificity among B.

Quantitative Control for Stoichiometric Protein Synthesis.

Bacterial protein synthesis rates have evolved to maintain preferred stoichiometries at striking precision, from the components of protein complexes to constituents of entire pathways. Setting relative protein production rates to be well within a factor of two requires concerted tuning of transcription, RNA turnover, and translation, allowing many potential regulatory strategies to achieve the preferred output. The last decade has seen a greatly expanded capacity for precise interrogation of each step of the central dogma genome-wide.

Keeping the Proportions of Protein Complex Components in Check.

How do cells maintain relative proportions of protein complex components? Advances in quantitative, genome-wide measurements have begun to shed light onto the roles of protein synthesis and degradation in establishing the precise proportions in living cells: on the one hand, ribosome profiling studies indicate that proteins are already produced in the correct relative proportions. On the other hand, proteomic studies found that many complexes contain subunits that are made in excess and subsequently degraded. Here, we discuss these seemingly contradictory findings, emerging principles, and remaining open questions.

Production of Protein-Complex Components Is Stoichiometric and Lacks General Feedback Regulation in Eukaryotes.

Constituents of multiprotein complexes are required at well-defined levels relative to each other. However, it remains unknown whether eukaryotic cells typically produce precise amounts of subunits, or instead rely on degradation to mitigate imprecise production. Here, we quantified the production rates of multiprotein complexes in unicellular and multicellular eukaryotes using ribosome profiling.

Evolutionary Convergence of Pathway-Specific Enzyme Expression Stoichiometry.

Coexpression of proteins in response to pathway-inducing signals is the founding paradigm of gene regulation. However, it remains unexplored whether the relative abundance of co-regulated proteins requires precise tuning. Here, we present large-scale analyses of protein stoichiometry and corresponding regulatory strategies for 21 pathways and 67-224 operons in divergent bacteria separated by 0.

Testing the role of charge and structure on the stability of peptide-porphyrin complexes.

This study aims to extend a structural and biophysical understanding of a coiled-coil based peptide model system that serves as a scaffold for the anionic porphyrin, TPPS4. This is part of an ongoing biomaterials effort to create photoelectronically active mesoscale fibrils for surface deposition and characterization of conductivity properties. The goals are two-fold: (1) to explore optimal basic side-chain moieties for tight binding to TPPS4 and (2) to test the binding of various metalated TPPS4 derivatives to our peptide model system.