430 research outputs found
Physical interaction between bacterial heat shock protein (Hsp) 90 and Hsp70 chaperones mediates their cooperative action to refold denatured proteins.
In eukaryotes, heat shock protein 90 (Hsp90) is an essential ATP-dependent molecular chaperone that associates with numerous client proteins. HtpG, a prokaryotic homolog of Hsp90, is essential for thermotolerance in cyanobacteria, and in vitro it suppresses the aggregation of denatured proteins efficiently. Understanding how the non-native client proteins bound to HtpG refold is of central importance to comprehend the essential role of HtpG under stress. Here, we demonstrate by yeast two-hybrid method, immunoprecipitation assays, and surface plasmon resonance techniques that HtpG physically interacts with DnaJ2 and DnaK2. DnaJ2, which belongs to the type II J-protein family, bound DnaK2 or HtpG with submicromolar affinity, and HtpG bound DnaK2 with micromolar affinity. Not only DnaJ2 but also HtpG enhanced the ATP hydrolysis by DnaK2. Although assisted by the DnaK2 chaperone system, HtpG enhanced native refolding of urea-denatured lactate dehydrogenase and heat-denatured glucose-6-phosphate dehydrogenase. HtpG did not substitute for DnaJ2 or GrpE in the DnaK2-assisted refolding of the denatured substrates. The heat-denatured malate dehydrogenase that did not refold by the assistance of the DnaK2 chaperone system alone was trapped by HtpG first and then transferred to DnaK2 where it refolded. Dissociation of substrates from HtpG was either ATP-dependent or -independent depending on the substrate, indicating the presence of two mechanisms of cooperative action between the HtpG and the DnaK2 chaperone system
Dynamic polarizability of rotating particles in electrorheological fluids
A rotating particle in electrorheological (ER) fluid leads to a displacement
of its polarization charges on the surface which relax towards the external
applied field , resulting in a steady-state polarization at an angle
with respect to . This dynamic effect has shown to affect the ER
fluids properties dramatically. In this paper, we develop a dynamic effective
medium theory (EMT) for a system containing rotating particles of finite volume
fraction. This is a generalization of established EMT to account for the
interactions between many rotating particles. While the theory is valid for
three dimensions, the results in a special two dimensional configuration show
that the system exhibits an off-diagonal polarization response, in addition to
a diagonal polarization response, which resembles the classic Hall effect. The
diagonal response monotonically decreases with an increasing rotational speed,
whereas the off-diagonal response exhibits a maximum at a reduced rotational
angular velocity comparing to the case of isolated rotating
particles. This implies a way of measurement on the interacting relaxation
time. The dependencies of the diagonal and off-diagonal responses on various
factors, such as , the volume fraction, and the dielectric contrast,
are discussed.Comment: 6 pages, 4 figures, accepted to J. Phys. Chem.
An on-bead tailing/ligation approach for sequencing resin-bound RNA libraries
Nucleic acids possess the unique property of being enzymatically amplifiable, and have therefore been a popular choice for the combinatorial selection of functional sequences, such as aptamers or ribozymes. However, amplification typically requires known sequence segments that serve as primer binding sites, which can be limiting for certain applications, like the screening of on-bead libraries. Here, we report a method to amplify and sequence on-bead RNA libraries that requires not more than five known nucleotides. A key element is the attachment of the starting nucleoside to the synthesis resin via the nucleobase, which leaves the 3′-OH group accessible to subsequent enzymatic manipulations. After split-and-mix synthesis of the oligonucleotide library and deprotection, a poly(A)-tail can be efficiently added to this free 3′-hydroxyl terminus by Escherichia coli poly(A) polymerase that serves as an anchored primer binding site for reverse transcription. The cDNA is joined to a DNA adapter by T4 DNA ligase. PCR amplification yielded single-band products that could be cloned and sequenced starting from individual polystyrene beads. The method described here makes the selection of functional RNAs from on-bead RNA libraries more attractive due to increased flexibility in library design, higher yields of full-length sequence on bead and robust sequence determination
Observation of Large CP Violation in the Neutral B Meson System
We present a measurement of the Standard Model CP violation parameter sin
2phi_1 based on a 29.1 fb^{-1} data sample collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
One neutral B meson is fully reconstructed as a J/psi Ks, psi(2S) Ks, chi_c1
Ks, eta_c Ks, J/psi K_L or J/psi K^{*0} decay and the flavor of the
accompanying B meson is identified from its decay products. From the asymmetry
in the distribution of the time intervals between the two B meson decay points,
we determine sin 2phi_1 = 0.99 +- 0.14(stat) +- 0.06(syst). We conclude that we
have observed CP violation in the neutral B meson system.Comment: 4 figures, to appear in Phys. Rev. Letter
A Measurement of the Branching Fraction for the Inclusive B --> X(s) gamma Decays with the Belle Detector
We have measured the branching fraction of the inclusive radiative B meson
decay B --> X(s) gamma to be Br(B->X(s)gamma)=(3.36 +/- 0.53(stat) +/-
0.42(sys) +0.50-0.54(th)) x 10^{-4}.
The result is based on a sample of 6.07 x 10^6 BBbar events collected at the
Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e^+e^-
storage ring.Comment: 14 pages, 6 Postsript figures, uses elsart.cl
Measurement of Inclusive Production of Neutral Pions from Upsilon(4S) Decays
Using the Belle detector operating at the KEKB e+e- storage ring, we have
measured the mean multiplicity and the momentum spectrum of neutral pions from
the decays of the Upsilon(4S) resonance. We measure a mean of 4.70 +/- 0.04 +/-
0.22 neutral pions per Upsilon(4S) decay.Comment: 15 pages, 4 figs. Submitted to Phys.Rev.
Measurement of the CP Violation Parameter sin(2phi_1) in B^0_d Meson Decays
We present a measurement of the Standard Model CP violation parameter
sin(2phi_1) based on a 10.5 fb^{-1} data sample collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric e+e- collider. One
neutral B meson is reconstructed in the J/psi K_S, psi(2S) K_S, chi_{c1} K_S,
eta_c K_S, J/psi K_L or J/psi pi^0 CP-eigenstate decay channel and the flavor
of the accompanying B meson is identified from its charged particle decay
products. From the asymmetry in the distribution of the time interval between
the two B-meson decay points, we determine sin(2phi_1) = 0.58 +0.32-0.34 (stat)
+0.09-0.10 (syst).Comment: LaTex, 13 pages, 3 figures, submitted to P.R.
Suicide in cancer patients in South East England from 1996 to 2005: a population-based study
BACKGROUND: Studies from around the world have shown that suicide risk is increased in cancer patients, but no previous detailed analysis has been carried out in England
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