Papers by Adrian Velazquez-Campoy
Nature Communications, 2016
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Assembly of the mature human immunodeficiency virus type 1 capsid involves the oligomerization of... more Assembly of the mature human immunodeficiency virus type 1 capsid involves the oligomerization of the capsid protein, CA. The C-terminal domain of CA, CTD, participates both in the formation of CA hexamers and in the joining of hexamers through homodimerization. Intact CA and the isolated CTD are able to homodimerize in solution with similar affinity (dissociation constant in the order of 10 µM); CTD homodimerization involves mainly an R-helical region. In this work, we show that first-generation gallic acid-triethylene glycol (GATG) dendrimers bind to CTD. The binding region is mainly formed by residues involved in the homodimerization interface of CTD. The dissociation constant of the dendrimer-CTD complexes is in the range of micromolar, as shown by ITC. Further, the affinity for CTD of some of the dendrimers is similar to that of synthetic peptides capable of binding to the dimerization region, and it is also similar to the homodimerization affinity of both CTD and CA. Moreover, one of the dendrimers, with a relatively large hydrophobic moiety at the dendritic branching (a benzoate), was able to hamper the assembly in vitro of the human immunodeficiency virus capsid. These results open the possibility of considering dendrimers as lead compounds for the development of antihuman immunodeficiency virus drugs targeting capsid assembly.
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Review of Scientific Instruments, 2000
In a previous article a comprehensive description of an isothermal titration microcalorimeter wit... more In a previous article a comprehensive description of an isothermal titration microcalorimeter with Peltier compensation was reported. This work deals with the characterization procedure and the operation mode. The transfer function parameters (time constants, calibration constants, and thermal properties of the system components) have been determined using a rigorous physical model for the microcalorimeter. To check the good performance of
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Journal of Thermal Analysis and Calorimetry, 1999
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Journal of Thermal Analysis and Calorimetry, 1998
... A. Cabrerizo-Vílchez 'Departamento de Fisica Aplicada. ... A discret... more ... A. Cabrerizo-Vílchez 'Departamento de Fisica Aplicada. ... A discrete or pulsed trans-fer function is used because the controller is a digital computer sampling the sig-nal with aperiod T. Flexibility and easiness of implementation of digital controls when compared to analogical ...
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Protein Science, 2000
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Thermochimica Acta, 2001
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Biochemistry, 2000
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Molecular & Cellular Proteomics, 2014
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FEBS letters, Jan 28, 2014
In addition to the standard NADPH thioredoxin reductases (NTRs), plants hold a plastidic NTR (NTR... more In addition to the standard NADPH thioredoxin reductases (NTRs), plants hold a plastidic NTR (NTRC), with a thioredoxin module fused at the C-terminus. NTRC is an efficient reductant of 2-Cys peroxiredoxins (2-Cys Prxs). The interaction of NTRC and chloroplastic thioredoxin x with 2-Cys Prxs has been confirmed in vivo, by bimolecular fluorescence complementation (BiFC) assays, and in vitro, by isothermal titration calorimetry (ITC) experiments. In comparison with thioredoxin x, NTRC interacts with 2-Cys Prx with higher affinity, both the thioredoxin and NTR domains of NTRC contributing significantly to this interaction, as demonstrated by using the NTR and thioredoxin modules of the enzyme expressed separately. The presence of the thioredoxin domain seems to prevent the interaction of NTRC with thioredoxin x.
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Biochimica et biophysica acta, Jan 21, 2016
Protein function is frequently modulated by post-translational modifications of specific residues... more Protein function is frequently modulated by post-translational modifications of specific residues. Cytochrome c, in particular, is phosphorylated in vivo at threonine 28 and serine 47. However, the effect of such modifications on the physiological functions of cytochrome c - namely, the transfer of electrons in the respiratory electron transport chain and the triggering of programmed cell death - is still unknown. Here we replace each of these two residues by aspartate, in order to mimic phosphorylation, and report the structural and functional changes in the resulting cytochrome c variants. We find that the T28D mutant causes a 30-mV decrease on the midpoint redox potential and lowers the affinity for the distal site of Arabidopsis thaliana cytochrome c1 in complex III. Both the T28D and S47D variants display a higher efficiency as electron donors for the cytochrome c oxidase activity of complex IV. In both protein mutants, the peroxidase activity is significantly higher, which is ...
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Journal of molecular biology, Jan 23, 2016
Xeroderma pigmentosum type G (XPG) proteins are involved in DNA lesion recognition and promotion ... more Xeroderma pigmentosum type G (XPG) proteins are involved in DNA lesion recognition and promotion of nucleotide excision repair (NER). Specific mutations in these proteins may lead to Cockayne syndrome, in which the patients may display severe developmental retardation and neurological abnormalities. No structural information is available for their spacer region or the C-terminal domain, which are important, respectively, for specific NER activity and substrate specificity, and nuclear translocation. Immunofluorescence studies suggested two specific regions of the XPG C-terminus as potential bipartite nuclear localization sequences, which would be responsible for its translocation to the nucleus by the classical nuclear import pathway mediated by importin-α (Impα). Thus, in order to test these hypotheses and gain insight into the structural basis for the nuclear import process for the XPG protein, we solved the crystal structures of complexes formed by the Impα and peptides correspon...
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Nature Communications, 2015
Inosine-5'-monophosphate dehydrogenase (IMPDH) plays key roles in purine ... more Inosine-5'-monophosphate dehydrogenase (IMPDH) plays key roles in purine nucleotide metabolism and cell proliferation. Although IMPDH is a widely studied therapeutic target, there is limited information about its physiological regulation. Using Ashbya gossypii as a model, we describe the molecular mechanism and the structural basis for the allosteric regulation of IMPDH by guanine nucleotides. We report that GTP and GDP bind to the regulatory Bateman domain, inducing octamers with compromised catalytic activity. Our data suggest that eukaryotic and prokaryotic IMPDHs might have developed different regulatory mechanisms, with GTP/GDP inhibiting only eukaryotic IMPDHs. Interestingly, mutations associated with human retinopathies map into the guanine nucleotide-binding sites including a previously undescribed non-canonical site and disrupt allosteric inhibition. Together, our results shed light on the mechanisms of the allosteric regulation of enzymes mediated by Bateman domains and provide a molecular basis for certain retinopathies, opening the door to new therapeutic approaches.
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... Arne Schön and Adrian Velazquez-Campoy as well as the research work presented in this paper w... more ... Arne Schön and Adrian Velazquez-Campoy as well as the research work presented in this paper were supported by grants GM 57144 and GM 56550 from the National Institutes of Health and grant MCB-0131241 from the National Science Foundation to Ernesto Freire. ...
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AIP Conference Proceedings, 2006
Unspecific Cooperative Ligand Binding to One‐Dimensional Lattice‐like Macromolecules. [AIP Confer... more Unspecific Cooperative Ligand Binding to One‐Dimensional Lattice‐like Macromolecules. [AIP Conference Proceedings 851, 162 (2006)]. AdrianVelazquez‐Campoy. Abstract. Unspecific ligand binding to one‐dimensional lattice ...
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Antioxidants & Redox Signaling, 2015
The ferric uptake regulator (Fur) is the main transcriptional regulator of genes involved in iron... more The ferric uptake regulator (Fur) is the main transcriptional regulator of genes involved in iron homeostasis in most prokaryotes. FurA from Anabaena sp. PCC 7120 contains five cysteine residues, four of them arranged in two redox-active CXXC motifs. The protein needs not only metal but also reducing conditions to remain fully active in vitro. Through a mutational study of the cysteine residues present in FurA, we have investigated their involvement in metal and DNA binding. Residue C(101) that belongs to a conserved CXXC motif plays an essential role in both metal and DNA binding activities in vitro. Substitution of C(101) by serine impairs DNA and metal binding abilities of FurA. Isothermal titration calorimetry measurements show that the redox state of C(101) is responsible for the protein ability to coordinate the metal corepressor. Moreover, the redox state of C(101) varies with the presence or absence of C(104) or C(133), suggesting that the environments of these cysteines are mutually interdependent. We propose that C(101) is part of a thiol/disulfide redox switch that determines FurA ability to bind the metal corepressor. This mechanism supports a novel feature of a Fur protein that emerges as a regulator, which connects the response to changes in the intracellular redox state and iron management in cyanobacteria. Antioxid. Redox Signal. 00, 000-000.
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Acta Crystallographica Section D Biological Crystallography, 2015
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Journal of Biological Chemistry, 2015
ATP synthesis is a critical and universal life process carried out by ATP synthases. Whereas euka... more ATP synthesis is a critical and universal life process carried out by ATP synthases. Whereas eukaryotic and prokaryotic ATP synthases are well characterized, archaeal ATP synthases are relatively poorly understood. The hyperthermophilic archaeal parasite, Nanoarcheaum equitans lacks several subunits of the ATP synthase and is suspected to be energetically dependent on its host, Ignicoccus hospitalis. This suggests that this ATP synthase might be a rudimentary machine. Here, we report the crystal structure and biophysical studies of the regulatory subunit, NeqB, the apo NeqAB, and NeqAB in complex with nucleotides, ADP and AMP-PNP. NeqB is approximately 20 amino acids shorter at its C-terminus than its homologs but this does not impede its binding with NeqA to form the complex. The heterodimeric NeqAB complex assumes a closed, rigid conformation irrespective of nucleotide binding; this differs from its homologs, which require conformational changes for catalytic activity. Thus, although N. equitans possesses an ATP synthase core A3B3 hexameric complex, it might not function as a bona fide ATP synthase.
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Langmuir : the ACS journal of surfaces and colloids, Jan 12, 2015
Bile salts (BS) are biosurfactants synthesized in the liver and secreted into the intestinal lume... more Bile salts (BS) are biosurfactants synthesized in the liver and secreted into the intestinal lumen where they solubilize cholesterol and other hydrophobic compounds facilitating their gastrointestinal absorption. Partition of BS toward biomembranes is an important step in both processes. Depending on the loading of the secreted BS micelles with endogeneous cholesterol and on the amount of cholesterol from diet, this may lead to the excretion or absorption of cholesterol, from cholesterol-saturated membranes in the liver or to gastrointestinal membranes, respectively. The partition of BS toward the gastrointestinal membranes may also affect the barrier properties of those membranes affecting the permeability for hydrophobic and amphiphilic compounds. Two important parameters in the interaction of the distinct BS with biomembranes are their partition coefficient and the rate of diffusion through the membrane. Altogether, they allow the calculation of BS local concentrations in the mem...
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Proceedings of the National Academy of Sciences, 2015
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Papers by Adrian Velazquez-Campoy