67 research outputs found
Legendre-transform structure derived from quantum theorems
Datos recopilados de la publicaciΓ³n electrΓ³nica.Texto completo arXiv:1101.4661By recourse to (i) the HellmannβFeynman theorem and (ii) the virial one, the information-optimizing principle based on Fisherβs information measure uncovers a Legendre-transform structure associated with SchrΓΆdingerβs equation, in close analogy with the structure that lies behind the standard thermodynamical formalism. The present developments provide new evidence for the information theoretical links based on Fisherβs measure that exist between SchrΓΆdingerβs equation, on the one hand, and thermodynamics/thermostatistics on the other hand.This work has been partially supported by the Programs FQM-2445 and FQM-207 of the Junta de
AndaluciaPeer reviewe
Parameter-free ansatz for inferring ground state wave functions of even potentials
Schr\"odinger's equation (SE) and the information-optimizing principle based
on Fisher's information measure (FIM) are intimately linked, which entails the
existence of a Legendre transform structure underlying the SE. In this
comunication we show that the existence of such an structure allows, via the
virial theorem, for the formulation of a parameter-free ground state's
SE-ansatz for a rather large family of potentials. The parameter-free nature of
the ansatz derives from the structural information it incorporates through its
Legendre properties
Feedback Inhibition in the PhoQ/PhoP Signaling System by a Membrane Peptide
The PhoQ/PhoP signaling system responds to low magnesium and the presence of certain cationic antimicrobial peptides. It regulates genes important for growth under these conditions, as well as additional genes important for virulence in many gram-negative pathogens. PhoQ is a sensor kinase that phosphorylates and activates the transcription factor PhoP. Since feedback inhibition is a common theme in stress-response circuits, we hypothesized that some members of the PhoP regulon may play such a role in the PhoQ/PhoP pathway. We therefore screened for PhoP-regulated genes that mediate feedback in this system. We found that deletion of mgrB (yobG), which encodes a 47 amino acid peptide, results in a potent increase in PhoP-regulated transcription. In addition, over-expression of mgrB decreased transcription at both high and low concentrations of magnesium. Localization and bacterial two-hybrid studies suggest that MgrB resides in the inner-membrane and interacts directly with PhoQ. We further show that MgrB homologs from Salmonella typhimurium and Yersinia pestis also repress PhoP-regulated transcription in these organisms. In cell regulatory circuits, feedback has been associated with modulating the induction kinetics and/or the cell-to-cell variability in response to stimulus. Interestingly, we found that elimination of MgrB-mediated feedback did not have a significant effect on the kinetics of reporter protein production and did not decrease the variability in expression among cells. Our results indicate MgrB is a broadly conserved membrane peptide that is a critical mediator of negative feedback in the PhoQ/PhoP circuit. This new regulator may function as a point of control that integrates additional input signals to modulate the activity of this important signaling system
Political Education in Croatian Secondary Schools: An Emergency Reaction to a Chaotic Context
RETRACTED ARTICLE: Meta-analysis of the associations between TNF-Ξ± or IL-6 gene polymorphisms and susceptibility to lung cancer
Evolution of a Bacterial Regulon Controlling Virulence and Mg2+ Homeostasis
Related organisms typically rely on orthologous regulatory proteins to respond to a given signal. However, the extent to which (or even if) the targets of shared regulatory proteins are maintained across species has remained largely unknown. This question is of particular significance in bacteria due to the widespread effects of horizontal gene transfer. Here, we address this question by investigating the regulons controlled by the DNA-binding PhoP protein, which governs virulence and Mg2+ homeostasis in several bacterial species. We establish that the ancestral PhoP protein directs largely different gene sets in ten analyzed species of the family Enterobacteriaceae, reflecting both regulation of species-specific targets and transcriptional rewiring of shared genes. The two targets directly activated by PhoP in all ten species (the most distant of which diverged >200 million years ago), and coding for the most conserved proteins are the phoPQ operon itself and the lipoprotein-encoding slyB gene, which decreases PhoP protein activity. The Mg2+-responsive PhoP protein dictates expression of Mg2+ transporters and of enzymes that modify Mg2+-binding sites in the cell envelope in most analyzed species. In contrast to the core PhoP regulon, which determines the amount of active PhoP and copes with the low Mg2+ stress, the variable members of the regulon contribute species-specific traits, a property shared with regulons controlled by dissimilar regulatory proteins and responding to different signals
Evolution of a Bacterial Regulon Controlling Virulence and Mg2+ Homeostasis
Related organisms typically rely on orthologous regulatory proteins to respond to a given signal. However, the extent to which (or even if) the targets of shared regulatory proteins are maintained across species has remained largely unknown. This question is of particular significance in bacteria due to the widespread effects of horizontal gene transfer. Here, we address this question by investigating the regulons controlled by the DNA-binding PhoP protein, which governs virulence and Mg2+ homeostasis in several bacterial species. We establish that the ancestral PhoP protein directs largely different gene sets in ten analyzed species of the family Enterobacteriaceae, reflecting both regulation of species-specific targets and transcriptional rewiring of shared genes. The two targets directly activated by PhoP in all ten species (the most distant of which diverged >200 million years ago), and coding for the most conserved proteins are the phoPQ operon itself and the lipoprotein-encoding slyB gene, which decreases PhoP protein activity. The Mg2+-responsive PhoP protein dictates expression of Mg2+ transporters and of enzymes that modify Mg2+-binding sites in the cell envelope in most analyzed species. In contrast to the core PhoP regulon, which determines the amount of active PhoP and copes with the low Mg2+ stress, the variable members of the regulon contribute species-specific traits, a property shared with regulons controlled by dissimilar regulatory proteins and responding to different signals
- β¦