Self-assembly of Escherichia coli phage shock protein A

The Phage shock protein (Psp) response is an extracytoplasmic stress response. The central component of this system is PspA, a protein that mediates the physiological response to membrane stress. PspA is also involved in regulating its own transcription and that of the psp operon, forming a positive feedback loop. PspA has been previously shown to oligomerise into higher-order species, including a 36-meric species with ring-like structure. In this study, we demonstrate that the ring-like PspA structures further self-assemble into rod-shaped complexes. These rod-like structures may play a scaffolding role in the maintenance of membrane integrity during phage shock protein response

Diffusive growth of a single droplet with three different boundary conditions

We study a single, motionless three-dimensional droplet growing by adsorption of diffusing monomers on a 2D substrate. The diffusing monomers are adsorbed at the aggregate perimeter of the droplet with different boundary conditions. Models with both an adsorption boundary condition and a radiation boundary condition, as well as a phenomenological model, are considered and solved in a quasistatic approximation. The latter two models allow particle detachment. In the short time limit, the droplet radius grows as a power of the time with exponents of 1/4, 1/2 and 3/4 for the models with adsorption, radiation and phenomenological boundary conditions, respectively. In the long time limit a universal growth rate as $[t/\ln(t)]^{1/3}$ is observed for the radius of the droplet for all models independent of the boundary conditions. This asymptotic behaviour was obtained by Krapivsky \cite{krapquasi} where a similarity variable approach was used to treat the growth of a droplet with an adsorption boundary condition based on a quasistatic approximation. Another boundary condition with a constant flux of monomers at the aggregate perimeter is also examined. The results exhibit a power law growth rate with an exponent of 1/3 for all times

Development of columbium alloy WC3015

Effect of changes in basic composition and additions of alloying elements on mechanical properties of niobium alloy WC301

A bidirectional fluorescent two-hybrid system for monitoring protein–protein interactions

Two-hybrid systems have been the cornerstone of research into protein–protein interactions, but these systems typically rely on life/death reporters that put additional selective pressure on the host organism, and potentially lead to false positives. Here we report a bidirectional fluorescence-based bacterial two- hybrid system that enables both the association and dissociation of a given protein–protein interaction to be monitored. The functionality of this system and its compatibility with FACS screening are demon- strated in the forward and reverse direction using known interacting protein-partners and their cyclic peptide inhibitors. The reported fluorescent two-hybrid system may be used in the forward direction for the identification of interacting protein partners, or as a reverse two-hybrid system for the high- throughput identification of protein–protein interaction inhibitors