The HEAT repeat protein Blm10 regulates the yeast proteasome by capping the core particle

AbstractPore channels of poly-carbonate membranes were recently used as biomimetic models to study the effect of confinement on silicate condensation, leading to the formation of silica tubes exhibiting a core-shell structure. In this work, we pre-immobilized lysozyme on the membrane pores, inducing the modification of the tube shell formation process, and variation in core particle size. These data strengthen previous assumptions on the role of interfacial interactions on the growth of the tube shell and indicate that such interactions also influence the core particle formation. Such approach therefore seems suitable to mimic the formation of silica/protein multilayers as found in several biomineralizing organisms

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Dynamic calculations of the core/shell structured Ising-type endohedral fullerenes: The effect of core and core/shell interaction

Modern Physics Letters B ◽

10.1142/s0217984917503079 ◽

2017 ◽

Vol 31 (33) ◽

pp. 1750307 ◽

Cited By ~ 2

Author(s):

Ersin Kantar

Keyword(s):

Magnetic Properties ◽

Magnetic Particles ◽

Stochastic Dynamics ◽

Mean Field Theory ◽

Mean Field ◽

Core Shell ◽

Core Particle ◽

Factors Affecting ◽

The Core ◽

First Order Phase

In this study, we examine by comparing the dynamic magnetic and hysteretic properties of Ising-type endohedral fullerene (EF) with various dopant magnetic particles confined within a spherical cage. The model of EF X@C[Formula: see text] with X = spin-1/2, spin-1 and spin-3/2 is proposed to study the effect of the nature of core particle on the magnetic properties. The results were obtained by mean-field theory as well as Glauber-type stochastic dynamics, and focused on the response of thermal and hysteretic behaviors of systems. The system exhibits second- and first-order phase transitions. In three different core cases, the system also exhibits type-II superconductivity behavior with a dynamic hysteresis curves of the core. All results display magnetic properties of the EF which strongly depend on the nature of core particle. Moreover, core particle and core/shell (C–S) interaction are proposed as the basic factors affecting the magnetic properties of EF system.

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Expression and Characterization of Full-length Human Huntingtin, an Elongated HEAT Repeat Protein

Journal of Biological Chemistry ◽

10.1074/jbc.m511007200 ◽

2006 ◽

Vol 281 (23) ◽

pp. 15916-15922 ◽

Cited By ~ 53

Author(s):

Wei Li ◽

Louise C. Serpell ◽

Wendy J. Carter ◽

David C. Rubinsztein ◽

James A. Huntington

Keyword(s):

Full Length ◽

Repeat Protein ◽

Heat Repeat

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Binding of HMG-I(Y) Imparts Architectural Specificity to a Positioned Nucleosome on the Promoter of the Human Interleukin-2 Receptor α Gene

Molecular and Cellular Biology ◽

10.1128/mcb.20.13.4666-4679.2000 ◽

2000 ◽

Vol 20 (13) ◽

pp. 4666-4679 ◽

Cited By ~ 42

Author(s):

R. Reeves ◽

W. J. Leonard ◽

M. S. Nissen

Keyword(s):

T Cell ◽

Transcriptional Activation ◽

Interleukin 2 ◽

Proximal Promoter ◽

Cell Mediated Immunity ◽

Core Particle ◽

The Core ◽

Interleukin 2 Receptor

ABSTRACT Transcriptional induction of the interleukin-2 receptor alpha-chain (IL-2Rα) gene is a key event regulating T-cell-mediated immunity in mammals. In vivo, the T-cell-restricted protein Elf-1 and the general architectural transcription factor HMG-I(Y) cooperate in transcriptional regulation of the human IL-2Rα gene by binding to a specific positive regulatory region (PRRII) in its proximal promoter. Employing chromatin reconstitution analyses, we demonstrate that the binding sites for both HMG-I(Y) and Elf-1 in the PRRII element are incorporated into a strongly positioned nucleosome in vitro. A variety of analytical techniques was used to determine that a stable core particle is positioned over most of the PRRII element and that this nucleosome exhibits only a limited amount of lateral translational mobility. Regardless of its translational setting, the in vitro position of the nucleosome is such that DNA recognition sequences for both HMG-I(Y) and Elf-1 are located on the surface of the core particle. Restriction nuclease accessibility analyses indicate that a similarly positioned nucleosome also exists on the PRRII element in unstimulated lymphocytes when the IL-2Rα gene is silent and suggest that this core particle is remodeled following transcriptional activation of the gene in vivo. In vitro experiments employing the chemical cleavage reagent 1,10-phenanthroline copper (II) covalently attached to its C-terminal end demonstrate that HMG-I(Y) protein binds to the positioned PRRII nucleosome in a direction-specific manner, thus imparting a distinct architectural configuration to the core particle. Together, these findings suggest a role for the HMG-I(Y) protein in assisting the remodeling of a critically positioned nucleosome on the PRRII promoter element during IL-2Rα transcriptional activation in lymphocytes in vivo.

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A simultaneous determination of the parameters of the core-particle model in 197Au

Nuclear Physics ◽

10.1016/0029-5582(66)90398-1 ◽

1966 ◽

Vol 79 (1) ◽

pp. 159-164 ◽

Cited By ~ 9

Author(s):

John M. McKinley ◽

Phillip M. Rinard

Keyword(s):

Simultaneous Determination ◽

Particle Model ◽

Core Particle ◽

The Core

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The Hsp70/Hsp90 Co-Chaperone Hop/Stip1 Shifts the Proteostatic Balance from Folding Towards Degradation

10.1101/562637 ◽

2019 ◽

Author(s):

Kaushik Bhattacharya ◽

Lorenz Weidenauer ◽

Tania Morán Luengo ◽

Pablo C. Echeverría ◽

Lilia Bernasconi ◽

...

Keyword(s):

Protein Folding ◽

Protein Aggregation ◽

Human Cell ◽

Molecular Chaperones ◽

Human Cell Lines ◽

Specific Function ◽

Core Particle ◽

Knock Out ◽

The Core

SUMMARYHop/Stip1/Sti1 is thought to be essential as a co-chaperone to facilitate substrate transfer between the Hsp70 and Hsp90 molecular chaperones. Despite this proposed key function for protein folding and maturation, it is not essential in a number of eukaryotes and bacteria lack an ortholog. We set out to identify and to characterize its eukaryote-specific function. Human cell lines and the budding yeast with deletions of the Hop/Sti1 gene display reduced proteasome activity due to inefficient capping of the core particle with regulatory particles. Unexpectedly, knock-out cells are more proficient at preventing protein aggregation and at promoting protein refolding. Without the restraint by Hop, a more efficient folding activity of the prokaryote-like Hsp70/Hsp90 complex, which can also be demonstrated in vitro, compensates for the proteasomal defect and ensures an alternate proteostatic equilibrium. Thus, cells may act on Hop to shift the proteostatic balance between folding and degradation.

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Repositioning septins within the core particle

10.1101/569251 ◽

2019 ◽

Cited By ~ 1

Author(s):

Deborah C. Mendonça ◽

Joci N. Macedo ◽

Rosangela Itri ◽

Samuel L. Guimaraes ◽

Fernando L. Barroso da Silva ◽

...

Keyword(s):

Lipid Bilayers ◽

Self Assembly ◽

Binding Proteins ◽

Structural Information ◽

Core Particle ◽

Affinity Tag ◽

The Core ◽

Gtp Binding ◽

True Structure ◽

Core Particles

AbstractSeptins are GTP binding proteins considered to be a novel component of the cytoskeleton. They polymerize into filaments based on hetero-oligomeric core particles which, in humans, are either hexamers or octamers composed of two copies each of either three or four different septins from the 13 available. Not all combinations are possible as it is believed that these must obey substitution rules which determine that different septins must be derived from four distinct and well-established sub-groups. Here, we have purified and characterized one such combinations, SEPT5-SEPT6-SEPT7, and used TEM to derive the first structural information concerning its assembly. The full complex was purified using an affinity tag attached to only one of its components (SEPT7) and was able to bind to and perturb lipid bilayers. Although the complex assembled into elongated hexameric particles, the position of SEPT5 was incompatible with that predicted by the reported structure of SEPT2-SEPT6-SEPT7 based on the substitution rules. MBP-fusion constructs for SEPT5 and SEPT2 and immuno-staining clearly show that these septins occupy the terminal positions of the SEPT5-SEPT6-SEPT7 and SEPT2-SEPT6-SEPT7 hexamers, respectively. In so doing they expose a so-called NC interface which we show to be more susceptible to perturbation at high salt concentrations. Our results show that the true structure of the hexamer is inverted with respect to that described previously and, as such, is more compatible with that reported for yeast. Taken together, our results suggest that the mechanisms involved in spontaneous self-assembly of septin core particles and their filaments deserve further reflection.

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