Role of Domain Interactions in the Collective Motion of Phosphoglycerate Kinase

ABSTRACT Protein function is governed by the underlying conformational dynamics of the molecule. The experimental and theoretical work leading to contemporary understanding of enzyme dynamics was mostly restricted to the large-scale movements of single-domain proteins. Collective movements resulting from a regulatory interplay between protein domains is often crucial for enzymatic activity. It is not clear, however, how our knowledge could be extended to describe collective near-equilibrium motions of multidomain enzymes. We examined the effect of domain interactions on the low temperature near equilibrium dynamics of the native state, using phosphoglycerate kinase as model protein. We measured thermal activation of tryptophan phosphorescence quenching to explore millisecond-range protein motions. The two protein domains of phosphoglycerate kinase correspond to two dynamic units, but interdomain interactions link the motion of the two domains. The effect of the interdomain interactions on the activation of motions in the individual domains is asymmetric. As the temperature of the frozen protein is increased from the cryogenic, motions of the N domain are activated first. This is a partial activation, however, and the full dynamics of the domain becomes activated only after the activation of the C domai

DNA Binding of Porphyrin Conjugates: Characteristics and Consequences

In the past few issues of Spore, we haven t been able to accommodate all your letters and photos in Mailbox. That s why we re carrying a handsome Mailbox this time and if you want even more readers letters in the next issue, grab your pens now!MailboxIn the past few issues of Spore, we haven t been able to accommodate all your letters and photos in Mailbox. That s why we re carrying a handsome Mailbox this time and if you want even more readers letters in the next issue, grab your..

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Temperature-dependent nanomechanics and topography of bacteriophage T7.

Viruses are nanoscale infectious agents, which may be inactivated by heat treatment. The global molecular mechanisms of virus inactivation and the thermally-induced structural changes in viruses are not fully understood. Here we measured the heat-induced changes in the properties of T7 bacteriophage particles exposed to two-stage (65 degrees C and 80 degrees C) thermal effect, by using AFM-based nanomechanical and topographical measurements. We found that exposure to 65 degrees C led to the release of genomic DNA and to the loss of the capsid tail, hence the T7 particles became destabilized. Further heating to 80 degrees C surprisingly led to an increase in mechanical stability, due likely to partial denaturation of the capsomeric proteins kept within the global capsid arrangement.IMPORTANCE Even though the loss of DNA, caused by heat treatment, destabilizes the T7 phage, its capsid is remarkably able to withstand high temperatures with a more-or-less intact global topographical structure. Thus, partial denaturation within the global structural constraints of the viral capsid may have a stabilizing effect. Understanding the structural design of viruses may help in constructing artificial nanocapsules for the packaging and delivery of materials under harsh environmental conditions

Role of Domain Interactions in the Collective Motion of Phosphoglycerate Kinase

Protein function is governed by the underlying conformational dynamics of the molecule. The experimental and theoretical work leading to contemporary understanding of enzyme dynamics was mostly restricted to the large-scale movements of single-domain proteins. Collective movements resulting from a regulatory interplay between protein domains is often crucial for enzymatic activity. It is not clear, however, how our knowledge could be extended to describe collective near-equilibrium motions of multidomain enzymes. We examined the effect of domain interactions on the low temperature near equilibrium dynamics of the native state, using phosphoglycerate kinase as model protein. We measured thermal activation of tryptophan phosphorescence quenching to explore millisecond-range protein motions. The two protein domains of phosphoglycerate kinase correspond to two dynamic units, but interdomain interactions link the motion of the two domains. The effect of the interdomain interactions on the activation of motions in the individual domains is asymmetric. As the temperature of the frozen protein is increased from the cryogenic, motions of the N domain are activated first. This is a partial activation, however, and the full dynamics of the domain becomes activated only after the activation of the C domain