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In its 88-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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Cest-2923 figure-2

The alpha/beta hydrolase fold is one of the most versatile structures in the protein realm according to the diversity of sequences adopting such a three dimensional architecture. We found that the versatility of a canonical alpha/beta-hydrolase fold, particularly that of the carboxylesterase Cest-2923 from the lactic acid bacterium Lactobacillus plantarum WCFS1, also extends to its oligomeric behavior in solution. Thus, we discovered that Cest-2923 exhibits a pH-dependent pleomorphic behaviour in solution involving monomers, canonical dimers and tetramers. Whereas at neutral pH the system is mainly shifted to dimeric species, at acidic conditions tetrameric species predominate. Interestingly, despite that these tetramers result from the association of canonical dimers, as commonly found in many other carboxylesterases from the hormone-sensitive lipase family, they can be defined as “non canonical” since they represent a different association mode. The observed associative behaviour is consistent with different crystallographic results of Cest-2923 from structural genomics consortia. Finally, we benefit from the presence of sulphate or acetate molecules (depending on the crystal form analysed) in the close vicinity of the nucleophile Ser116, to identify interactions with the putative oxyanion hole and also to deduce the existence of hydrolytic activity within Cest-2923 crystals.

 

 

Reference:
Benavente R, Esteban-Torres M, Acebrón I, de Las Rivas B, Muñoz R, Alvarez Y, Mancheño JM. “Structure, biochemical characterization and analysis of the pleomorphism of carboxylesterase Cest-2923 from Lactobacillus plantarum WCFS1”. FEBS J. 2013 Oct 16. doi: 10.1111/febs.12569.

 

summary figure
Magnetite is a magnetic material known since more than two thousand years ago. It presents a phase transition known as the Verwey transition (at ~ 120K), in which the crystal structure changes from cubic to monoclinic, and at the same time the conductivity is reduced by two orders of magnitude. This transition strongly promoted research on metal-insulator transitions. For the first time, a team of researchers from the IQFR, Berkeley National Laboratory and the Vienna Technical University have observed this transition with surface-sensitive microscopies for the (100) orientation of magnetite. It has been found that the surface "rumbles" forming a roof-like surface at a micrometer scale, whereas the actual surface reconstruction has the same structure through the transition. This indicates that although the surface reconstruction is conceptually similar to the bulk structure below the transition, they are two distinct phenomena.
 
J. de la Figuera, Z. Novotny, M. Setvin, T. Liu, Z. Mao, G. Chen, A. T. N'Diaye, M. Schmid, U. Diebold, A. K. Schmid, G. S. Parkinson,  "Real Space Imaging of the Verwey Transition at the (100) Surface of Magnetite", Phys. Rev. B 88 (2013) 161410(R), DOI:10.1103/PhysRevB.88.161410,  arxiv 1310.1373
 
The figure shows at the top, low-energy electron microscope images (8.6 um wide) above (left) and below (right) the Verwey transition. In the middle, scanning tunneling microscopy images with atomic resolution are shown also above and below the transition. At the bottom, a profile showns the "roof" surface below the transition.
 
 
 

Exocytosis and Endocytosis; from membranes and molecules to mechanisms

Date: 28th Nov 2013, 15:30. Room 300

Activities for Week of Science

Date: Thursday 14th November, 10:30 - 14:00 horas
10:30 - 12:00 Talks at the Hall Conference Room
12:00 - 14:00 Visits to laboratories

"The role of Gbp2p, Nab2p and Pub1p along the mRNA cycle: structural and molecular recognition studies by NMR and other biophysical techniques"

Date: Friday 15th November, 12:00
Place: Salón de Actos

surface-cov-1-green-01

The expression of penicillin binding protein 2a (PBP2a) is the basis for the broad clinical resistance to the β-lactam antibiotics by methicillin-resistant Staphylococcus aureus (MRSA). The highmolecular mass penicillin binding proteins of bacteria catalyze in separate domains the transglycosylase and transpeptidase activities required for the biosynthesis of the peptidoglycan polymer that comprises the bacterial cell wall. In bacteria susceptible to β-lactam antibiotics, the transpeptidase activity of their penicillin binding proteins (PBPs) is lost as a result of irreversible acylation of an active site serine by the β-lactam antibiotics. In contrast, the PBP2a of MRSA is resistant to β-lactamacylation and successfully catalyzes the DD-transpeptidation reaction necessary to complete the cell wall. The inability to contain MRSA infection with β-lactam antibiotics is a continuing public health concern. We report herein the identification of an allosteric binding domain—a remarkable 60 Å distant from the DD-transpeptidase active site—discovered by crystallographic analysis of a soluble construct of PBP2a. When this allosteric site is occupied, a multiresidue conformational change culminates in the opening of the active site to permit substrate entry. This same crystallographic analysis also reveals the identity of three allosteric ligands: muramic acid (a saccharide component of the peptidoglycan), the cell Wall peptidoglycan, and ceftaroline, a recently approved anti-MRSA β-lactam antibiotic. The ability of an anti-MRSA β-lactam antibiotic to stimulate allosteric opening of the active site, thus predisposing PBP2a to inactivation by a second β-lactam molecule, opens an unprecedented realm for β-lactam antibiotic structure-based design.

Reference:

Lisandro H. Oteroa, Alzoray Rojas-Altuvea, Leticia I. Llarrull, Cesar Carrasco-López, Malika Kumarasiri, Elena Lastochkin, Jennifer Fishovitz, Matthew Dawley, Dusan Hesek, Mijoon Lee, Jarrod W. Johnson, Jed F. Fisher, Mayland Chang, Shahriar Mobashery, Juan A. Hermoso. How allosteric control of Staphylococcus aureus penicillin binding protein 2a enables methicillin resistance and physiological function. PNAS. DOI: 10.1073/pnas.1300118110

 

dosuno

Modified nucleic acids are very interesting molecules because of their application in Biomedicine, as therapeutic agents, and in Nanoscience, as potential components of nano-devices. Of particular relevance is the substitution of a hydrogen atom at the 2’ position of the DNA deoxyribose by fluorine. Fluorine is the most electronegative element and alters the electronic distribution in its surroundings, provoking interactions that are not present, or are much weaker, in natural nucleic acids.

In two recent papers researchers of the IQFR, in collaboration with colleagues of McGill University in Canada and in the IRB in Barcelona, have described these effects at structural level and analysed their physico-chemical basis in double helical and guanine quadruplex structures.

 

Reference:

N. Martín-Pintado, M. Yahyaee-Anzahaee, G. F. Deleavey, G. Portella, M. Orozco, M.J. Damha, and C. González.Dramatic effect of furanose C2´-substitution on structure and stability:  Directing the folding of the human telomeric quadruplex with a single fluorine atom.J. Am. Chem. Soc., 135, 5344-5347, 2013.doi: 10.1021/ja401954t

N. Martín-Pintado, G. F. Deleavey, G. Portella, R. Campos-Olivas, M. Orozco, M.J. Damha, and C. González.Backbone FC-H...O hydrogen bonds in 2´F-substituted nucleic acids.Angewandte Chemie Int Ed, en prensa, 2013.doi:10.1002/anie.201305710

 

arriba

abajo

Scientists from the Department of Biophysical Chemistry discovered novel water-soluble oxocines and azocines that produce blue fluorescence with 100% quantum yield. These molecules are the main product of a new fluorogenic reaction that converts non-emitting biocompounds as L-DOPA, dopamine, hydroxytyrosol, etc. into useful photostable fluorophores. The new molecular structures contain the rare four-ring chromophore which originated the first written account of fluorescence emission in 1565 (Acuña et al. Org. Lett. 2009, 11, 3020). At that time, the medical doctor N. Monardes from Sevilla reported the unusual blue “color” (fluorescence) of the infusion of a medicinal wood widely used in preHispanic Aztec culture.

 

Reference:

Synthesis and photophysics of novel biocompatible fluorescent oxocines and azocines in aqueous solution.

A.Ulises Acuña, Mónica Älvarez-Pérez, Marta Liras, Pedro B. Coto and Francisco Amat-Guerri.

Phys. Chem. Chem. Phys. Sept. 2013 (DOI: 10:1039/c3cp52228h)