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Arcuri H.A.,Discipline of Allergy and Immunology INCor HC FMUSP | Arcuri H.A.,Sao Paulo State University | Palma M.S.,Sao Paulo State University | Palma M.S.,National Institute of Science and Technology on Immunology INCT iii
Current Medicinal Chemistry | Year: 2011

Tuberculosis is considered a worldwide health problem mainly due to co-infection with HIV and proliferation of multi-drugresistant strains. The enzymes of the shikimate pathway are potential targets for the development of new therapies because they are essential for bacteria, but absent from mammals. The last step in this pathway is performed by chorismate synthase (CS), which catalyzes the conversion of 5-enolpyruvylshikimate-3-phosphate (EPSP) to chorismate. The aim of this article is to review the available information on chorismate synthase from Mycobacterium tuberculosis. © 2011 Bentham Science Publishers Ltd.

Bernardes A.,University of Sao Paulo | Batista F.A.H.,University of Sao Paulo | de Oliveira Neto M.,University of Sao Paulo | Figueira A.C.M.,National Laboratory of Biosciences | And 6 more authors.
PLoS ONE | Year: 2012

The peroxisome proliferator-activated receptors (PPARs) regulate genes involved in lipid and carbohydrate metabolism, and are targets of drugs approved for human use. Whereas the crystallographic structure of the complex of full length PPARγ and RXRα is known, structural alterations induced by heterodimer formation and DNA contacts are not well understood. Herein, we report a small-angle X-ray scattering analysis of the oligomeric state of hPPARγ alone and in the presence of retinoid X receptor (RXR). The results reveal that, in contrast with other studied nuclear receptors, which predominantly form dimers in solution, hPPARγ remains in the monomeric form by itself but forms heterodimers with hRXRα. The low-resolution models of hPPARγ/RXRα complexes predict significant changes in opening angle between heterodimerization partners (LBD) and extended and asymmetric shape of the dimer (LBD-DBD) as compared with X-ray structure of the full-length receptor bound to DNA. These differences between our SAXS models and the high-resolution crystallographic structure might suggest that there are different conformations of functional heterodimer complex in solution. Accordingly, hydrogen/deuterium exchange experiments reveal that the heterodimer binding to DNA promotes more compact and less solvent-accessible conformation of the receptor complex. © 2012 Bernardes et al.

Saidemberg D.M.,Sao Paulo State University | Saidemberg D.M.,National Institute of Science and Technology on Immunology INCT iii | Passarelli A.W.,Sao Paulo State University | Passarelli A.W.,National Institute of Science and Technology on Immunology INCT iii | And 8 more authors.
Current Medicinal Chemistry | Year: 2011

The enzymes of the shikimate pathway represent potential molecular targets for the development of non-toxic antimicrobial agents and anti-parasite drugs. One of the most promising of these enzymes is shikimate kinase (EC, which is responsible for the fifth step in the shikimate pathway. This enzyme phosphorylates shikimic acid to yield shikimate-3-phosphate, using ATP as a substrate. In this work, the conformational dynamics of the shikimate kinase from Mycobacterium tuberculosis was investigated in its apostate in solution. For this study, the enzyme was subjected to a gradient of temperatures from 15° C to 45 ° C in the presence or absence of deuterium oxide, and the amide H/D exchange was monitored using ESI-mass spectrometry. We observed: i) the phosphate binding domain in the apo-enzyme is fairly rigid and largely protected from solvent access, even at relatively high temperatures; ii) the shikimate binding domain is highly flexible, as indicated by the tendency of the apo-enzyme to exhibit large conformational changes to permit LID closure after the shikimate binding; iii) the nucleotide binding domain is initially conformationally rigid, which seems to favour the initial orientation of ADP/ATP, but becomes highly flexible at temperatures above 30°C, which may permit domain rotation; iv) part of the LID domain, including the phosphate binding site, is partially rigid, while another part is highly flexible and accessible to the solvent. © 2011 Bentham Science Publishers Ltd.

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