The study of polyoxometalates formation using capillary zone electrophoresis.

The formation process of polyoxometalates [PMo12 O40 ](3-) and [PMo12 - x Vx O40 ](-3-x) has been studied in aqueous solutions of 0.1 M malonate buffer at pH 2.8-3.

Structure and mechanism of the saposin-like domain of a plant aspartic protease.

Many plant aspartic proteases contain an additional sequence of ~100 amino acids termed the plant-specific insert, which is involved in host defense and vacuolar targeting. Similar to all saposin-like proteins, the plant-specific insert functions via protein-membrane interactions; however, the structural basis for such interactions has not been studied, and the nature of plant-specific insert-mediated membrane disruption has not been characterized. In the present study, the crystal structure of the saposin-like domain of potato aspartic protease was resolved at a resolution of 1.

Crystal structure of human interferon-λ1 in complex with its high-affinity receptor interferon-λR1.

Interferon (IFN)-λ1 [also known as interleukin (IL)-29] belongs to the recently discovered group of type III IFNs. All type III IFNs initiate signaling processes through formation of specific heterodimeric receptor complexes consisting of IFN-λR1 and IL-10R2. We have determined the structure of human IFN-λ1 complexed with human IFN-λR1, a receptor unique to type III IFNs.

Structural analysis of cytokines comprising the IL-10 family.

Interleukin-10 (IL-10) family of cytokines includes a number of its viral homologs and eight cellular cytokines (IL-19, IL-20, IL-22, IL-24, IL-26, IL-28A, IL-28B, and IL-29). The latter three proteins are also known as IFN-λ2, IFN-λ3, and IFN-λ1, and are recognized as type III (or λ) interferons. Most of the cellular homologs of IL-10 are monomeric in solution, whereas IL-10 and its viral homologs are intercalated dimers consisting of two helical bundle domains topologically similar to the monomeric members of the family.

Effect of host genetics on the development of cytomegalovirus retinitis in patients with AIDS.

Background: Cytomegalovirus (CMV) retinitis is a common opportunistic infection among patients with AIDS and still causes visual morbidity despite the wide spread usage of highly active antiretroviral therapy (HAART). The ubiquitous CMV pathogen contains a human interleukin-10 (IL-10) homolog in its genome and utilizes it to evade host immune reactions through an IL-10 receptor mediated immune-suppression pathway.

Methods: Effects of IL-10R1, IL-10 and previously described AIDS restriction gene variants are investigated on the development of CMV retinitis in the Longitudinal Study of the Ocular Complications of AIDS (LSOCA) cohort (N = 1284).

Purification, crystallization and preliminary crystallographic studies of the complex of interferon-lambda1 with its receptor.

Human interferon-lambda1 (IFN-lambda1(Ins)) and the extracellular domain of interferon-lambda1 receptor (IFN-lambda1R1) were expressed in Drosophila S2 cells and purified to homogeneity. Both IFN-lambda1(Ins) and interferon-lambda1 produced from Escherichia coli (IFN-lambda1(Bac)) were coupled with IFN-lambda1R1 at room temperature and the complexes were purified by gel filtration. Both complexes were crystallized; the crystals were flash-frozen at 100 K and diffraction data were collected to 2.

Structure of the lamin A/C R482W mutant responsible for dominant familial partial lipodystrophy (FPLD).

Proteins of the A-type lamin family, which consists of two members, lamin A and lamin C, are the major components of a thin proteinaceous filamentous meshwork, the lamina, that underlies the inner nuclear membrane. A-type lamins have recently become the focus of extensive functional studies as a consequence of the linking of at least eight congenital diseases to mutations in the lamin A/C gene (LMNA). This spectrum of pathologies, which mostly manifest themselves as dominant traits, includes muscle dystrophies, dilated cardiomyopathies, the premature aging syndrome Hutchinson-Guilford progeria and familial partial lipodystrophy (FPLD).

Differential signaling of cmvIL-10 through common variants of the IL-10 receptor 1.

Human IL-10 (hIL-10) signaling is mediated by receptors consisting of two subunits, IL-10 receptor 1 (IL-10R1) and IL-10 receptor 2. Two common variants of the IL-10R1 (Ser 138 Gly (single-nucleotide polymorphism 3, SNP3) and Gly 330 Arg (SNP4)) are associated with diverse disease phenotypes. Viral homologs to hIL-10, such as cmvIL-10, utilize the same IL-10 receptor complex as part of viral immune evasion strategies.

A new look at cytokine signaling.

Signal transduction is initiated when a cytokine binds to the extracellular domains of its receptors, bringing them together and triggering a complicated sequence of events inside the cell. In this issue, LaPorte et al. (2008) present crystal structures of three signaling complexes of the cytokines interleukin-4 and interleukin-13 with their receptors, showing how events taking place outside the cell may affect the specificity of signal transduction.

Structural studies of the interleukin-19 subfamily of cytokines.

The interleukin-19 (IL-19) subfamily of cytokines is part of a larger family of homologs of IL-10 that includes two groups of proteins: five viral cytokines, and eight cellular cytokines, having quite different biological activities. Among proteins of the latter group, IL-19, IL-20, IL-22, and IL-24 were suggested to form a structurally unique IL-19 subfamily characterized by their structural features and aggregation state as monomers. IFN-lambda1, IFN-lambda2, and IFN-lambda3 are likely to belong to this subfamily, and it is still not clear whether IL-26 belongs to it or not.

A model of the ternary complex of interleukin-10 with its soluble receptors.

Background: Interleukin-10 (IL-10) is a cytokine whose main biological function is to suppress the immune response by induction of a signal(s) leading to inhibition of synthesis of a number of cytokines and their cellular receptors. Signal transduction is initiated upon formation of a ternary complex of IL-10 with two of its receptor chains, IL-10R1 and IL-10R2, expressed on the cell membrane. The affinity of IL-10R1 toward IL-10 is very high, which allowed determination of the crystal structure of IL-10 complexed with the extracellular/soluble domain of IL-10R1, while the affinity of IL-10R2 toward either IL-10 or IL-10/sIL-10R1 complex is quite low.

Structural features of the interleukin-10 family of cytokines.

The interleukin-10 (IL-10) family of cytokines includes IL-10, a number of its viral gene homologs, and eight recently discovered cellular cytokines (IL-19, IL-20, IL-22, IL-24, IL-26, IFN-lambda1, IFN-lambda2, IFN-lambda3). IL-10 is an intercalated dimer consisting of two six-helix bundle domains. Signal transduction occurs when each domain of IL-10 binds to two receptor chains, IL-10R1 and IL-10R2.

Cutting edge: IL-26 signals through a novel receptor complex composed of IL-20 receptor 1 and IL-10 receptor 2.

The receptor for IL-26 (AK155), a cytokine of the IL-10 family, has not previously been defined. We demonstrate that the active receptor complex for IL-26 is a heterodimer composed of two receptor proteins: IL-20R1 and IL-10R2. Signaling through the IL-26R results in activation of STAT1 and STAT3 which can be blocked by neutralizing Abs against IL-20R1 or IL-10R2.

Characterization of the recombinant extracellular domains of human interleukin-20 receptors and their complexes with interleukin-19 and interleukin-20.

The soluble extracellular domains of human interleukin-20 (IL-20) receptors I and II (sIL-20R1 and sIL20R2), along with their ligands IL-19 and IL-20, were expressed in Drosophila S2 cells and purified to homogeneity. Formation of the receptor/receptor and ligand/receptor complexes was studied by size exclusion chromatography. Both ligands and soluble receptors were found to be monomeric in solution; homo- or heterodimers are not formed even at elevated concentrations.

Control of tetrapyrrole biosynthesis by alternate quaternary forms of porphobilinogen synthase.

Porphobilinogen synthase (PBGS) catalyzes the first common step in the biosynthesis of tetrapyrroles (such as heme and chlorophyll). Although the predominant oligomeric form of this enzyme, as inferred from many crystal structures, is that of a homo-octamer, a rare human PBGS allele, F12L, reveals the presence of a hexameric form. Rearrangement of an N-terminal arm is responsible for this oligomeric switch, which results in profound changes in kinetic behavior.

Novel variants of the IL-10 receptor 1 affect inhibition of monocyte TNF-alpha production.

IL-10-deficient mice exhibit spontaneous enterocolitis and other symptoms akin to Crohn's disease, indicating that IL-10 might regulate normal physiology in the gut. However, clinical trials with IL-10 in Crohn's disease were disappointing, although some patients showed healing of intestinal mucosa. This study searched for genetic polymorphisms within the IL-10 pathway.

Crystal structure of interleukin-19 defines a new subfamily of helical cytokines.

Interleukin-19 (IL-19) is a novel cytokine that was initially identified during a sequence data base search aimed at finding potential IL-10 homologs. IL-19 shares a receptor complex with IL-20, indicating that the biological activities of these two cytokines overlap and that both may play an important role in regulating development and proper functioning of the skin. We determined the crystal structure of human recombinant IL-19 and refined it at 1.

Structural basis for the substrate specificity of tobacco etch virus protease.

Because of its stringent sequence specificity, the 3C-type protease from tobacco etch virus (TEV) is frequently used to remove affinity tags from recombinant proteins. It is unclear, however, exactly how TEV protease recognizes its substrates with such high selectivity. The crystal structures of two TEV protease mutants, inactive C151A and autolysis-resistant S219D, have now been solved at 2.

Species-specific inhibition of porphobilinogen synthase by 4-oxosebacic acid.

Porphobilinogen synthase (PBGS) catalyzes the condensation of two molecules of 5-aminolevulinic acid (ALA), an essential step in tetrapyrrole biosynthesis. 4-Oxosebacic acid (4-OSA) and 4,7-dioxosebacic acid (4,7-DOSA) are bisubstrate reaction intermediate analogs for PBGS. We show that 4-OSA is an active site-directed irreversible inhibitor for Escherichia coli PBGS, whereas human, pea, Pseudomonas aeruginosa, and Bradyrhizobium japonicum PBGS are insensitive to inhibition by 4-OSA.

A conserved glutamate residue exhibits multifunctional catalytic roles in D-fructose-1,6-bisphosphate aldolases.

The aldolase catalytic cycle consists of a number of proton transfers that interconvert covalent enzyme intermediates. Glu-187 is a conserved amino acid that is located in the mammalian fructose-1,6-bisphosphate aldolase active site. Its central location, within hydrogen bonding distance of three other conserved active site residues: Lys-146, Glu-189, and Schiff base-forming Lys-229, makes it an ideal candidate for mediating proton transfers.

Structure and mechanism of activity of the cyclic phosphodiesterase of Appr>p, a product of the tRNA splicing reaction.

The crystal structure of the cyclic phosphodiesterase (CPDase) from Arabidopsis thaliana, an enzyme involved in the tRNA splicing pathway, was determined at 2.5 A resolution. CPDase hydrolyzes ADP-ribose 1",2"-cyclic phosphate (Appr>p), a product of the tRNA splicing reaction, to the monoester ADP-ribose 1"-phosphate (Appr-1"p).

Crystal structure of plant aspartic proteinase prophytepsin: inactivation and vacuolar targeting.

We determined at 2.3 A resolution the crystal structure of prophytepsin, a zymogen of a barley vacuolar aspartic proteinase. In addition to the classical pepsin-like bilobal main body of phytepsin, we also traced most of the propeptide, as well as an independent plant-specific domain, never before described in structural terms.

Purification of receptor complexes of interleukin-10 stoichiometry and the importance of deglycosylation in their crystallization.

Interleukin-10 (IL-10) is a pleiotropic immunosuppressive cytokine that has a wide range of effects in controlling inflammatory responses. Viral IL-10 (vIL-10) is a homologue of human IL-10 (hIL-10) produced by Epstein-Barr virus (EBV). Both hIL-10 and vIL-10 bind to the soluble extracellular fragment of the cytokine receptor IL-10R1 (shIL-10R1).