cAMP is an allosteric modulator of DNA-binding specificity in the cAMP receptor protein from Mycobacterium tuberculosis.

Allosteric proteins with multiple subunits and ligand-binding sites are central in regulating biological signals. The cAMP receptor protein from Mycobacterium tuberculosis (CRP) is a global regulator of transcription composed of two identical subunits, each one harboring structurally conserved cAMP- and DNA-binding sites. The mechanisms by which these four binding sites are allosterically coupled in CRP remain unclear.

Non-invasive Neurite Mechanics in Differentiated PC12 Cells.

Thermal Fluctuations Spectroscopy (TFS) in combination with novel optical-based instrumentation was used to study mechanical properties of cell-cultured neurites with a spatial resolution limited only by the light diffraction. The analysis of thermal fluctuations together with a physical model of cellular elasticity allow us to determine relevant mechanical properties of neurite as axial tension σ, flexural rigidity , plasma membrane tension γ, membrane bending rigidity , and cytoskeleton to membrane-coupling ρ , whose values are consistent with previously reported values measured using invasive approaches. The value obtained for the membrane-coupling parameter was used to estimate the average number of coupling elements between the plasma membrane and the cytoskeleton that fell in the range of 30 elements per area of the laser spot used to record the fluctuations.

Asymmetric configurations in a reengineered homodimer reveal multiple subunit communication pathways in protein allostery.

Many allosteric proteins form homo-oligomeric complexes to regulate a biological function. In homo-oligomers, subunits establish communication pathways that are modulated by external stimuli like ligand binding. A challenge for dissecting the communication mechanisms in homo-oligomers is identifying intermediate liganded states, which are typically transiently populated.

Time-resolved neurite mechanics by thermal fluctuation assessments.

In the absence of simple noninvasive measurements, the knowledge of temporal and spatial variations of axons mechanics remains scarce. By extending thermal fluctuation spectroscopy (TFS) to long protrusions, we determine the transverse amplitude thermal fluctuation spectra that allow direct and simultaneous access to three key mechanics parameters: axial tension, bending flexural rigidity and plasma membrane tension. To test our model, we use PC12 cell protrusions-a well-know biophysical model of axons-in order to simplify the biological system under scope.