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In its 85-year story, the mission of our institute has been to carry out excellence research in fundamental and applied physical chemistry, contributing to the scientific training of several generations of researchers at the highest level. Our vision is to be an international reference in multidisciplinary research focused on the resolution of the present challenges of our society in the fields of health, biotechnology, new materials, and environment.

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magnetiteMagnetite is the material used to track the history of the Earth magnetic field. Thus its magnetism, and especially its changes with temperature, have attracted a long-standing interest. Magnetite undergoes several phase transitions, some purely magnetic, like the spin-reorientation transition (typically at 130-140K) where the magnetization changes direction, and others, like the Verwey transition, a metal-insulator transition due to a change in the crystal structure, from cubic to monoclinic. We have recently employed novel microscopy techniques to observe the changes of magnetic domains due to these transitions: one, spin-polarized low-energy electron microscopy (SPLEEM), of which there are four instruments in the world, in collaboration with Andreas K. Schmid and coworkers from the Berkeley National Laboratory, and the other, spin-resolved photoemission electron microscopy (spin-PEEM), of which there is currently only one instrument, at the Max Planck Insitute for Microstructure Physics (Halle), in collaboration with Christian Tusche. Upper left-hand figure: SPLEEM image of the magnetic domains below the Verwey temperature, color-coded for the orientation of the magnetization as shown in the circle below (1). Right-hand figure: spin-PEEM image (2) of the magnetization above (upper image) and below (lower image) the Verwey temperature. These techniques allowed us to obtain images with nm resolution of the magnetic domains below and above the transition temperature.

(1) Laura Martín-García, Arantzazu Mascaraque, Beatriz M. Pabón, Roland Bliem, Gareth S. Parkinson, Gong Chen (陈宫), Andreas K. Schmid, and Juan de la Figuera, "Spin reorientation transition on magnetite (001)", Phys. Rev. B 93 (2016) 134419, DOI:10.1103/PhysRevB.93.134419

(2) J. de la Figuera and C. Tusche, "The Verwey transition observed by spin-resolved photoemission electron microscopy", App. Surf. Sci. (2016), DOI:10.1016/j.apsusc.2016.05.140

 

web page figure

Amyotrophic Lateral Sclerosis (ALS) is a mortal neuromuscular disease that affects 2800 persons in Spain, with two new cases being diagnosed each day. Abnormal aggregates of the protein “TDP-43” (transactive response DNA binding protein 43 kDa) are found in >95% of dying motor neurons, and have been linked to other neurodegenerative disease, including Alzheimer’s disease and Frontotemporal Lobar Degeneration. Aggregation of TDP-43 was traced to a small, Asn- and Gln-rich region of the protein spanning residues 341-357, but the conformation of this segment and how it oligomerizes into harmful aggregates was unknown. Here, on the basis of multiple biochemical assays and biophysical experiments, IQFR investigators in collaboration with scientists from Columbia University (New York), the Cajal Institute (CSIC), IMDEA Nanoscience (CAM), and the International Centre for Genetic Engineering and Biotechnology (Trieste, IT) show that this segment’s beta hairpin motifs assemble into an amyloid-like structure with an unusual fibril morphology. Using computational methods, they have advanced an amyloid-like structural model for the aggregate in which TDP-43 (341-357) beta hairpins dock in a novel, parallel topology. This structural model will likely aid our understanding of TDP-43’s role in neurodegenerative diseases and may help guide the search for treatments.

M. Mompeán, R. Hervás, Y. Xu, T.H. Tran, C. Guarnaccia, E. Buratti, F. Baralle, L. Tong, M. Carrión-Vázquez, A.E. McDermott, D.V. Laurents 
J. Phys. Chem. Letters, June 2015, doi: 10.1021/acs.jpclett.5b00918

 

Fig2IQFRweb 24June2015

Autolysin LytA is a protein involved in the virulence of pneumococcus, a pathogenic microorganism in humans. Its C-terminal domain (CLytA) consists of six choline-binding repeats (CBR), arranged in the β-solenoid structure characteristic of choline-binding modules. In the NMR group of the Institute of Physical-Chemistry ‘Rocasolano’ (CSIC) we have structurally characterised a 14-residue peptide encompassing the sequence of the core β-hairpin from the third CBR repeat of CLytA. It has been found that this peptide conserves its native β-hairpin fold in aqueous solution, but forms a stable, amphipathic α-helix (i.e. with two faces, one hydrophobic and the other polar) in detergent micelles (with a hydrophilic surface and a hydrophobic core). These β-hairpin and α-helix structures differ greatly in the distribution of polar hydrophobic side chains. As far as we know, this "chameleonic" behaviour of a micelle-induced structural transition between two ordered peptide structures has not been reported before, and shows the dramatic effect of hydrophobic-hydrophilic interactions. These results could not only be of relevance in the field of peptide design and biosensors, but may also help to understand the molecular basis for the peculiar mechanism of LytA translocation from the cytoplasm to the bacterial surface.
Reference:

 

Hector Zamora-Carreras, Beatriz Maestro, Erik Strandberg, Anne S. Ulrich, Jesús M. Sanz, y M. Angeles Jiménez. “Micelle-triggered β-hairpin to α-helix transition in a 14-residue peptide derived from the pneumococcal choline-binding protein LytA”. Chemistry-Eur J. 21, 8076-8089 (2015). doi:10.1002/chem.201500447
Enlace a artículos destacados en mayo 2015 por la SBE (http://biofisica.info/zamora-carreras-jimenez-chemistry-21-8076/

 

"A Strategy to Accelerate Diabetic Wound Healing"
Mayland Chang
Department of Chemistry and Biochemistry
University of Notre Dame, Indiana, USA

Martes, 30 de Junio de 2015
Hora: 12:00 Salón de Actos

Contacto: Juan A. Hermoso

Julia-Sanz-figura2

Plant cell walls are highly complex structures of interlocking polysaccharides that are recalcitrant to biological degradation. Within the complex molecular machinery involved in its deconstruction, one of the greatest challenges is to decipher the mechanism that display enzymes with multiple copies of ancillary non-catalytic domains. Most of these domains are Carbohydrate Binding Modules (CBMs). Homogeneous multimodularity has been related to multivalency and avidity effects, while heterogeneous pattern is supposed to provide distinct substrate-binding specificities. However, recent work suggests that this panorama may be more complex. Researchers at IQFR have performed structural and functional studies on a large xylanase (Xyn10c) showing a distinctive modular structure that contains an N-terminal tandem of two CBM22s and a duplicated CMB9 at its C-terminus. We have discovered novel features that attribute a different functionality to each CBM22 module and suggest a deliver strategy of Xyn10C mediated by its CBM22 tandem. Our work will contribute to unravel the mechanisms ruling modularity, which is essential to understand the biomass recycling and to produce efficient biocatalysts. This will result in more environmentally sustainable industries.

The Journal of Biological Chemistry (2015)
First published in May 22
(doi:10.1074/jbc.M115.659300)

 

CoverJBC Def small2

Glycoproteins gp120 and gp41 are part of the AIDS HIV virus envelope. These proteins are involved in both, virus / host cell membrane fusion, a step essential for viral infection, and in the immune response to the virus. The knowledge of the structure of these proteins is crucial to understand these mechanisms at molecular level.
Scientists from the NMR group at the Institute of Physical-Chemistry ‘Rocasolano’ (CSIC), in collaboration with Dr. J. L. Nieva (University of the Basque Country) and Dr. J.M.M. Caaveiro (University of Tokyo) have determined the structure of several peptides reproducing sequences of the MPER (membrane-proximal external region) and TM (trans-membrane) sub-domains of the HIV gp41 protein. This work shows that the structure of the trans-membrane region, which has not been solved previously, presents two helices connected by a flexible segment. In addition, it has been found that the final MPER region and the initial TM region form a unique uninterrupted helix, in contrast to bioinformatics prediction. A model for the mechanism of virus / host cell membrane fusion has been proposed on the basis of these structural data. More interestingly, these data also explain the observed differences in antibody affinity, as well as the immune response of MPER-derived peptides. Accordingly, this information would be of great interest for a rational design of novel vaccines and inhibitors, useful as alternative therapies against AIDS.
The work has been selected as “Paper of the Week” by the editors of J. Biol. Chem.
Virion and envelope glycoprotein contour images were kindly provided by Dr. S. Subramaniam.
Reference:
B. Apellaniz, E. Rojas, S. Serrano, K. Morante, K. Tsumoto, J.M.M. Caaveiro, M.A. Jiménez, & J.L. Nieva. “The atomic structure of the HIV-1 gp41 MPER-TMD region reveals a continuously helical inter-domain connection flanked by two metastable hinge segments. Implications for MPER immunogenicity”. J. Biol. Chem. (2015). doi:10.1074/jbc.M115.644351.
Link to CSIC news

 

"Explorando Patrones de Glicosilación de Bacterias Patógenas y Vesículas Extracelulares como Marcadores para Receptores Endógenos"

Miércoles 11 de junio

Salón de actos, 12:00

Estructura de vacantes de oxígeno en el óxido de cerio reducible y función catalíticauna perspectiva teórica del papel de la localización del exceso de carga



Viernes 6 de junio

Aula 300, 10:30

Las galectinas: tan parecidas, tan diferentes

Thursday June 27th 2013

12:00 Salón de Actos

"Actividades de investigación en el Grupo de Química Atmosférica y Clima"

Thursday 20th June 2013

12:00 Salón de Actos de IQFR

"Estudios mediante RMN de la estructura y estabilidad de ácidos nucleicos con furanosas modificada"

Tuesday 18th June  2013

12:00 Salón de Actos del IQRF

"From Bayes (to electrons to proteins) to therapies"

Wednesday 19th, 2013

12:00 Salón de Actos

Modelado y simulación de procesos de adsorción en arcillas con pilares intercalados

12:00 Salón de Actos

Wednesday, June 12th 2013

Water: A Fluid Complex
16:00 Aula 300

Miércoles 12 Junio 2013

figura webScientists from IQFR have revealed the inhibition mechanism of UDG, a key enzyme for DNA repair. The work has been developed in collaboration with scientists from CBMSO (CSIC-UAM).

 

UDG is the first enzyme acting in a specific DNA repair pathway, called BER, where it detects uracil in DNA. Once detected, uracil is removed and subsequent enzymes within the BER pathway continue the process. Several proteins have been identified capable to inhibit UDG, among them p56 encoded by different phages probably as a defence mechanism.

 

p56 is a DNA mimic protein that blocks the UDG active site. The structure of the complex showed a specific recognition pattern between UDG and p56 that explains the lack of cross-reactivity among p566 and other DNA binding proteins. Therefore, our results shed light onto the UDG-blocking mechanism used by some viruses to proliferate into the host cell. Moreover, they pave the way to the potential use of p56 as antiviral agent against some infectious caused by herpes and poxvirus.

Publication:
José Ignacio Baños-Sanz, Laura Mojardín, Julia Sanz-Aparicio, José M. Lázaro, Laurentino Villar, Gemma Serrano-Heras, Beatriz González*, and Margarita Salas*.
Crystal structure and functional insights into uracil-DNA glycosylase inhibition by phage ϕ29 DNA mimic protein p56
Nucl. Acids Res. 2013 doi:10.1093/nar/gkt395