Ribosomes are the factories in cells that synthesize proteins. When cells grow faster, there are not enough ribosomes to keep up with the demand for faster protein synthesis without individual ribosomes becoming more productive.

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A key atmospheric process that is studied in laboratory chambers is the oxidation of volatile organic compounds to form low volatility products that condense on existing atmospheric particles (or nucleate) to form organic aerosol, so-called secondary organic aerosol. The laboratory chamber operates as a chemical reactor, in which a number of chemical and physical processes take place: gas-phase chemistry, transport of vapor oxidation products to suspended particles followed by uptake into the particles, deposition of vapors on the walls of the chamber, deposition of particles on the walls of the chamber, and coagulation of suspended particles. Understanding the complex interplay among these simultaneous physicochemical processes is necessary in order to interpret the results of chamber experiments. Here we develop and utilize a comprehensive computational model for dynamics of vapors and particles in a laboratory chamber and analyze chamber behavior over a range of physicochemical conditions.

Research on protein-protein interaction (PPIs) tends to focus on high affinity interactions. Weaker interactions (Kd > 1 µM) recently understood as contributing to intracellular phase separation suggest that even-weaker PPIs might also matter in as-yet unknown ways. However, ultra-weak PPIs (Kd > 1 mM) are not readily accessible by in vivo techniques. Here we use protein electrostatics to estimate PPI strengths and spatially-resolved dynamic simulations to investigate the potential impacts of ultra-weak PPIs within dense protein suspensions. We find that ultra-weak PPIs can drive formation of transient clusters that last long enough to enable enzyme-catalyzed reactions and accelerate the sampling of protein associations. We apply our method to Mycoplasma genitalium , finding that ultra-weak PPIs should be ubiquitous among cytoplasmic proteins. We also predict that the proteome-wide interactome can be shifted to favor 'binding-dominant' ultra-weak PPIs via the introduction of a few charged protein complexes. We speculate that ultra-weak PPIs could contribute to cellular fitness by facilitating sampling and colloidal-scale transport of proteins involved in biological processes, including protein synthesis.

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