Long-Term Care Home Size Association with COVID-19 Infection and Mortality in Catalonia in March and April 2020.

We aim to assess how COVID-19 infection and mortality varied according to facility size in 965 long-term care homes (LTCHs) in Catalonia during March and April 2020. We measured LTCH size by the number of authorised beds. Outcomes were COVID-19 infection (at least one COVID-19 case in an LTCH) and COVID-19 mortality.

The Impact of Long-Term Care Home Ownership and Administration Type on All-Cause Mortality from March to April 2020 in Madrid, Spain.

Our aim is to assess whether long-term care home (LTCH) ownership and administration type were associated with all-cause mortality in 470 LTCHs in the Community of Madrid (Spain) during March and April 2020, the first two months of the COVID-19 pandemic. There are eight categories of LTCH type, including various combinations of ownership type (for-profit, nonprofit, and public) and administration type (completely private, private with places rented by the public sector, administrative management by procurement, and completely public). Multilevel regression was used to examine the association between mortality and LTCH type, adjusting for LTCH size, the spread of the COVID-19 infection, and the referral hospital.

The solution structure of the N-terminal domain of human tubulin binding cofactor C reveals a platform for tubulin interaction.

Human Tubulin Binding Cofactor C (TBCC) is a post-chaperonin involved in the folding and assembly of α- and β-tubulin monomers leading to the release of productive tubulin heterodimers ready to polymerize into microtubules. In this process it collaborates with other cofactors (TBC's A, B, D, and E) and forms a supercomplex with TBCD, β-tubulin, TBCE and α-tubulin. Here, we demonstrate that TBCC depletion results in multipolar spindles and mitotic failure.

Characterization of the structure and self-recognition of the human centrosomal protein NA14: implications for stability and function.

The protein NA14 is a key adaptor protein mediating the intermolecular interactions of microtubules and Spastin. To gain insight into its structure and function, we have expressed, purified and characterized human NA14 and some variants. NA14 is rather insoluble and tends to oligomerize and form fibrils.

NMR structural determinants of eosinophil cationic protein binding to membrane and heparin mimetics.

Eosinophil cationic protein (ECP) is a highly stable, cytotoxic ribonuclease with the ability to enter and disrupt membranes that participates in innate immune defense against parasites but also kills human cells. We have used NMR spectroscopy to characterize the binding of ECP to membrane and heparin mimetics at a residue level. We believe we have identified three Arg-rich surface loops and Trp(35) as crucial for membrane binding.

A bacterial antirepressor with SH3 domain topology mimics operator DNA in sequestering the repressor DNA recognition helix.

Direct targeting of critical DNA-binding elements of a repressor by its cognate antirepressor is an effective means to sequester the repressor and remove a transcription initiation block. Structural descriptions for this, though often proposed for bacterial and phage repressor-antirepressor systems, are unavailable. Here, we describe the structural and functional basis of how the Myxococcus xanthus CarS antirepressor recognizes and neutralizes its cognate repressors to turn on a photo-inducible promoter.

Structural characterisation of the natively unfolded enterocin EJ97.

Bacteriocins belong to the wide variety of antimicrobial ribosomal peptides synthesised by bacteria. Enterococci are Gram-positive, catalase-negative bacteria that produce lactic acid as the major end product of glucose fermentation. Many enterococcal strains produce bacteriocins, named enterocins.

NMR characterisation of the minimal interacting regions of centrosomal proteins 4.1R and NuMA1: effect of phosphorylation.

Background: Some functions of 4.1R in non-erythroid cells are directly related with its distinct sub-cellular localisation during cell cycle phases. During mitosis, 4.

The (1)H, (13)C, (15)N resonance assignment, solution structure, and residue level stability of eosinophil cationic protein/RNase 3 determined by NMR spectroscopy.

Eosinophil cationic protein (ECP)/human RNase 3, a member of the RNase A family, is a remarkably cytotoxic protein implicated in asthma and allergies. These activities are probably due to ECP's ability to interact with and disrupt membranes and depend on two Trp, 19 Arg, and possibly an extremely high conformational stability. Here, we have used NMR spectroscopy to assign essentially all (1)H, (15)N, and backbone (13)C resonances, to solve the 3D structure in aqueous solution and to quantify its residue-level stability.

Interaction between the N-terminal SH3 domain of Nck-alpha and CD3-epsilon-derived peptides: non-canonical and canonical recognition motifs.

The first SH3 domain (SH3.1) of Nckalpha specifically recognizes the proline-rich region of CD3varepsilon, a subunit of the T cell receptor complex. We have solved the NMR structure of Nckalpha SH3.

Destabilizing mutations alter the hydrogen exchange mechanism in ribonuclease A.

The effect of strongly destabilizing mutations, I106A and V108G of Ribonuclease A (RNase A), on its structure and stability has been determined by NMR. The solution structures of these variants are essentially equivalent to RNase A. The exchange rates of the most protected amide protons in RNase A (35 degrees C), the I106A variant (35 degrees C), and the V108G variant (10 degrees C) yield stability values of 9.

Solution structure of the C-terminal domain of Ole e 9, a major allergen of olive pollen.

Ole e 9 is an olive pollen allergen belonging to group 2 of pathogenesis-related proteins. The protein is composed of two immunological independent domains: an N-terminal domain (NtD) with 1,3-beta-glucanase activity, and a C-terminal domain (CtD) that binds 1,3-beta-glucans. We have determined the three-dimensional structure of CtD-Ole e 9 (101 amino acids), which consists of two parallel alpha-helices forming an angle of approximately 55 degrees , a small antiparallel beta-sheet with two short strands, and a 3-10 helix turn, all connected by long coil segments, resembling a novel type of folding among allergens.

Context-dependence of the contribution of disulfide bonds to beta-hairpin stability.

Incorporation of disulfide bonds to stabilize protein and peptide structures is not always a successful strategy. To advance current knowledge on the contribution of disulfide bonds to beta-hairpin stability, a previously reported beta-hairpin-forming peptide was taken as a template to design a series of Cys-containing peptides. The conformational behavior of these peptides in their oxidized, disulfide-cyclized peptides, and reduced, linear peptides, was investigated on the basis of NMR parameters: NOEs, and 1H and 13C chemical shifts.

Solution structure of the hypothetical protein TA0095 from Thermoplasma acidophilum: a novel superfamily with a two-layer sandwich architecture.

TA0095 is a 96-residue hypothetical protein from Thermoplasma acidophilum that exhibits no sequence similarity to any protein of known structure. Also, TA0095 is a member of the COG4004 orthologous group of unknown function found in Archaea bacteria. We determined its three-dimensional structure by NMR methods.

Structural basis for operator and antirepressor recognition by Myxococcus xanthus CarA repressor.

Blue light induces carotenogenesis in Myxococcus xanthus. The carB operon encodes all but one of the structural genes involved, and its expression is regulated by the CarA-CarS repressor-antirepressor pair. In the dark, CarA-operator binding represses carB.

pH-Dependent conformational stability of the ribotoxin alpha-sarcin and four active site charge substitution variants.

Alpha-sarcin is an exquisitely specific ribonuclease that binds and cleaves a single phosphodiester bond in the large rRNA of the eukaryotic ribosome, inactivating it. To better understand this remarkable activity, the contributions of the active site residues (His 50, Glu 96, and His 137) to the conformational stability have been determined as a function of pH using variant proteins containing uncharged substitutes. Wild-type alpha-sarcin and the variants are maximally stable near pH 5.

Assessing the protonation state of drug molecules: the case of aztreonam.

Herein we examine the viability of physicochemical approaches based on standard computational chemistry tools to characterize the structure and energetics of flexible drug molecules with various titratable sites. We focus on the case of the monobactam antibiotic aztreonam, whose structure and physicochemical properties have been ascribed to several tautomeric forms, although it is still unclear which protonation states are responsible for its biological activity. First, we experimentally determined the pKa values for aztreonam over the pH range 0.

Induced-fit recognition of DNA by small circular oligonucleotides.

We have investigated the molecular interaction between cyclic and linear oligonucleotides. We have found that short cyclic oligonucleotides can induce hairpinlike structures in linear DNA fragments. By using NMR and CD spectroscopy we have studied the interaction of the cyclic oligonucleotide d with d, as well as with its two linear analogs d(GTCCCTCA) and d(CTCAGTCC).

Formation, structure, and dissociation of the ribonuclease S three-dimensional domain-swapped dimer.

Post-translational events, such as proteolysis, are believed to play essential roles in amyloid formation in vivo. Ribonuclease A forms oligomers by the three-dimensional domain-swapping mechanism. Here, we demonstrate the ability of ribonuclease S, a proteolytically cleaved form of ribonuclease A, to oligomerize efficiently.

Beta-hairpin formation in aqueous solution and in the presence of trifluoroethanol: a (1)H and (13)C nuclear magnetic resonance conformational study of designed peptides.

In order to check our current knowledge on the principles involved in beta-hairpin formation, we have modified the sequence of a 3:5 beta-hairpin forming peptide with two different purposes, first to increase the stability of the formed 3:5 beta-hairpin, and second to convert the 3:5 beta-hairpin into a 2:2 beta-hairpin. The conformational behavior of the designed peptides was investigated in aqueous solution and in 30% trifluoroethanol (TFE) by analysis of the following nuclear magnetic resonance (NMR) parameters: nuclear Overhauser effect (NOE) data, and C(alpha)H, (13)C(alpha), and (13)C(beta) conformational shifts. From the differences in the ability to adopt beta-hairpin structures in these peptides, we have arrived to the following conclusions: (i) beta-Hairpin population increases with the statistical propensity of residues to occupy each turn position.

Charge substitution shows that repulsive electrostatic interactions impede the oligomerization of Alzheimer amyloid peptides.

The strong pH dependence of A beta oligomerization could arise from favorable intermolecular charge-charge interactions between His and carboxylate groups, or, alternatively, by mutual electrostatic repulsion of peptide molecules. To test between these two possibilities, the pH dependence of the oligomerization of A beta and three charge substitution variants with Asp, Glu and His substituted by Ala is measured. All four peptides oligomerize, as detected by thioflavin T fluorescence, turbidity, and amyloid fibril formation; therefore, specific charge-charge interactions are nonessential for oligomerization.

Ribonuclease Sa conformational stability studied by NMR-monitored hydrogen exchange.

The conformational stability of ribonuclease Sa (RNase Sa) has been measured at the per-residue level by NMR-monitored hydrogen exchange at pH* 5.5 and 30 degrees C. In these conditions, the exchange mechanism was found to be EXII.

Refined NMR structure of alpha-sarcin by 15N-1H residual dipolar couplings.

(15)N-(1)H residual dipolar couplings (RDC) have been used as additional restraints to refine the solution structure of the ribotoxin alpha-sarcin. The RDC values were obtained by partial alignment of alpha-sarcin in the binary mixture of n-dodecyl hexa(ethylene glycol)/hexanol. A total of 131 RDCs were measured and 106 were introduced in the final steps of the calculation protocol following the main calculation based on nuclear Overhauser enhancements and torsion angle restraints.