Force Distribution Reveals Signal Transduction in E. coli Hsp90

AbstractHeat-shock protein 90 (Hsp90) is an ubiquitous chaperone that is essential for cell function in that it promotes client-protein folding and stabilization. Its function is tightly controlled by an ATP-dependent large conformational transition between the open and closed states of the Hsp90 dimer. The underlying allosteric pathway has remained largely unknown, but it is revealed here in atomistic detail for the Escherichia coli homolog HtpG. Using force-distribution analysis based on molecular-dynamics simulations (>1 μs in total), we identify an internal signaling pathway that spans from the nucleotide-binding site to an ∼2.3-nm-distant region in the HtpG middle domain, that serves as a dynamic hinge region, and to a putative client-protein-binding site in the middle domain. The force transmission is triggered by ATP capturing a magnesium ion and thereby rotating and bending a proximal long α-helix, which represents the major force channel into the middle domain. This allosteric mechanism is, with statistical significance, distinct from the dynamics in the ADP and apo states. Tracking the distribution of forces is likely to be a promising tool for understanding and guiding experiments of complex allosteric proteins in general

Dynamical calculation of d∗d^* mass and NN decay width in the quark delocalization, color screening model

The mass estimate of the $d^* (IJ^P=03^+)$ dibaryon is improved by a dynamical calculation in the quark delocalization, color screening model. The partial decay width of $d^*$ into an $NN$ D-wave state is also obtained. The mass obtained is slightly larger than that obtained in adiabatic calculations, due to the anharmonicity of the effective potential between two $\Delta$'s. The value of the width obtained due to tensor one-gluon-exchange is about 5 MeV, comparable in magnitude to earlier results found using pion exchange.Comment: 11 pages, no figures, additional reference

Monokulare Visuelle Odometrie auf Multisensorplattformen für autonome Fahrzeuge

In dieser Arbeit werden die Grenzen aktueller Odometrieschätzung mithilfe monokularer Kamerasysteme identifiziert und erweitert. Die Basis bildet der Bündelblockausgleich, für welchen Punkte in zeitlichem Bildsequenzen verfolgt werden. Hieraus wird sowohl die Kamerabewegung geschätzt als auch die Umgebungsstruktur rekonstruiert. Mithilfe eines LIDAR wird die Tiefeninformation zu den Kameradaten extrahiert und in das Optimierungsproblem integriert

An Allosteric Signaling Pathway of Human 3-Phosphoglycerate Kinase from Force Distribution Analysis

3-Phosphogycerate kinase (PGK) is a two domain enzyme, which transfers a phosphate group between its two substrates, 1,3-bisphosphoglycerate bound to the N-domain and ADP bound to the C-domain. Indispensable for the phosphoryl transfer reaction is a large conformational change from an inactive open to an active closed conformation via a hinge motion that should bring substrates into close proximity. The allosteric pathway resulting in the active closed conformation has only been partially uncovered. Using Molecular Dynamics simulations combined with Force Distribution Analysis (FDA), we describe an allosteric pathway, which connects the substrate binding sites to the interdomain hinge region. Glu192 of alpha-helix 7 and Gly394 of loop L14 act as hinge points, at which these two secondary structure elements straighten, thereby moving the substrate-binding domains towards each other. The long-range allosteric pathway regulating hPGK catalytic activity, which is partially validated and can be further tested by mutagenesis, highlights the virtue of monitoring internal forces to reveal signal propagation, even if only minor conformational distortions, such as helix bending, initiate the large functional rearrangement of the macromolecule. © 2014 Palmai et al

Resonant behaviour in double charge exchange reaction of \pi^+ mesons on the nuclear photoemulsion

The invariant mass spectra of the $pp\pi^-$ and $pp$ systems produced in the double charge exchange (DCX) of positively charged pions on photoemulsion are analysed. A pronounced peak is observed in the $pp\pi^-$ invariant mass spectrum, while the $M_{pp}$ spectrum exhibits a strong Migdal-Watson effect of the proton-proton final state interaction. These findings are in favor of the $NN$-decoupled $NN\pi$ pseudoscalar resonance with T=0 called $d'$.Comment: 13 pages, 5 figures, revised versio