Dynamics of Neurotoxin II Provides Adaptivity of its Functional Sites

Abstract

Phosphorylation by cAMP dependent Protein Kinase A (PKA) is a ubiquitous signaling enzyme that regulates a variety of cellular functions. The regulatory and the catalysis subunits of PKA exist as a holoenzyme in an inactive state until cAMP releases the catalytic subunit (PKA-C). PKA is the prototypical kinase and has served as a benchmark for allosteric signaling in kinases. Previous work has demonstrated that binding of the nucleotide to PKA-C acts as a dynamic activator for the kinase, who's structural dynamics are retained by substrate selection and is quenched by binding of an inhibitor. However the thermodynamic basis for the selection of ligand and substrate for kinase function is not fully understood and ongoing research has suggested that this is a critical aspect of drug discovery. Here we investigate the allosteric activation of PKA-C upon binding various nucleotides using a combination of thermodynamic data and NMR spin relaxation measurements of the kinase side-chain methyl groups.

Characterization of Lipid–Protein Interactions and Lipid-Mediated Modulation of Membrane Protein Function through Molecular Simulation

“…590 Similar to the smaller toxins discussed above, it was found that membrane binding of α-neurotoxin facilitates its delivery to the receptor, in a study combining NMR spectroscopy and MD simulation. 591 In particular, specific interactions with the anionic DOPS lipids promoted a specific "standing" orientation of α-neurotoxin on the membrane suitable for receptor inhibition. 591 Interestingly, cardiotoxins are structurally homologous to neurotoxins but confer less toxicity and are believed to interact with intracellular components in addition to membrane targets.…”

“…591 In particular, specific interactions with the anionic DOPS lipids promoted a specific "standing" orientation of α-neurotoxin on the membrane suitable for receptor inhibition. 591 Interestingly, cardiotoxins are structurally homologous to neurotoxins but confer less toxicity and are believed to interact with intracellular components in addition to membrane targets. MD simulations have been used to explore membrane association modes and membrane penetration mechanisms for cobra cardiotoxin CTX A3.…”