IQFR-CSIC

News

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We will have a get-together to give our farewell to Isabel Cabo as manager of the Institute. It will take place at the hall in front of room 300 at 13:00-13:30.

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“How do pneumococci and other bacteria subvert the function of human proteins”

Friday 29th, 12:00

Room 300

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The respiratory pathogen Streptococcus pneumoniae has evolved efficient mechanisms to resist oxidative stress conditions and to displace other bacteria in the nasopharynx. Here we characterize at physiological, functional and structural levels two novel surface-exposed thioredoxin-family lipoproteins, Etrx1 and Etrx2. The impact of both Etrx proteins and their redox partner methionine sulfoxide reductase SpMsrAB2 on pneumococcal pathogenesis was assessed in mouse virulence studies and phagocytosis assays. The results demonstrate that loss of function of either both Etrx proteins or SpMsrAB2 dramatically attenuated pneumococcal virulence in the acute mouse pneumonia model and that Etrx proteins compensate each other. The deficiency of Etrx proteins or SpMsrAB2 further enhanced bacterial uptake by macrophages, and accelerated pneumococcal killing by H2O2 or free methionine sulfoxides (MetSO). Moreover, the absence of both Etrx redox pathways provokes an accumulation of oxidized SpMsrAB2 in vivo. Taken together our results reveal insights into the role of two extracellular electron pathways required for reduction of SpMsrAB2 and surface-exposed MetSO. Identification of this system and its target proteins paves the way for the design of novel antimicrobials.

Reference:
Malek Saleh, Sergio G. Bartual, Mohammed R. Abdullah, Inga Jensch, Tauseef M. Asmat, Lothar Petruschka, Thomas Pribyl, Juan A. Hermoso* and Sven Hammerschmidt*
Molecular architecture of Streptococcus pneumoniae surface thioredoxin-fold lipoproteins crucial for extracellular oxidative stress resistance and maintenance of virulence
EMBO Molecular Medicine (2013) 5, 1852-1870 (doi:10.1002/emmm.201202435)

Referencia:

Malek Saleh, Sergio G. Bartual, Mohammed R. Abdullah, Inga Jensch, Tauseef M. Asmat, Lothar Petruschka, Thomas Pribyl, Juan A. Hermoso* and Sven Hammerschmidt*

Molecular architecture of Streptococcus pneumoniae surface thioredoxin-fold lipoproteins crucial for extracellular oxidative stress resistance and maintenance of virulence

EMBO Molecular Medicine (2013) 5, 1852-1870 (doi:10.1002/emmm.201202435)

Details: Category: News

We will have the traditional yearly meeting to briefly review 2013 at the main conference rooma t 13:00 and an informal lunch afterwards.

Details: Category: Research

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.

Details: Category: Research

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.