90-day mortality risk related to postoperative potassium levels in patients undergoing coronary bypass surgery.

Aims: While electrolyte depletion is known to occur during coronary artery bypass grafting (CABG) with extracorporeal circulation, little is known about the frequency of potassium disturbances following either on- or off-pump CABG and its association with mortality. We examined the frequency of potassium disturbances and the association of plasma potassium with mortality risk in patients following CABG.

Methods And Results: From Danish National Registries, we identified 6123 adult patients (≥18 years old) undergoing first-time CABG, and who had a registered potassium measurement within 14 days before and 7 days after their surgery between 1995 and 2018.

Distinct colony boundaries and larval discrimination in polygyne red imported fire ants (Solenopsis invicta).

Evaluating the factors that promote invasive ant abundance is critical to assess their ecological impact and inform their management. Many invasive ant species show reduced nestmate recognition and an absence of boundaries between unrelated nests, which allow populations to achieve greater densities due to reduced intraspecific competition. We examined nestmate discrimination and colony boundaries in introduced populations of the red imported fire ant (Solenopsis invicta; hereafter, fire ant).

Red imported fire ant (Solenopsis invicta) aggression influences the behavior of three hard tick species.

Few studies have documented the indirect effects of predators on tick behavior. We conducted behavioral assays in the laboratory to quantify the effects of a highly abundant predator, the red imported fire ant (Solenopsis invicta), on three species of ticks endemic to the southern USA: the lone star tick (Amblyomma americanum), the Gulf Coast tick (A. maculatum), and the Cayenne tick (A.

Structural insights into the bacterial carbon-phosphorus lyase machinery.

Phosphorus is required for all life and microorganisms can extract it from their environment through several metabolic pathways. When phosphate is in limited supply, some bacteria are able to use phosphonate compounds, which require specialized enzymatic machinery to break the stable carbon-phosphorus (C-P) bond. Despite its importance, the details of how this machinery catabolizes phosphonates remain unknown.

The shapes of Z-α1-antitrypsin polymers in solution support the C-terminal domain-swap mechanism of polymerization.

Emphysema and liver cirrhosis can be caused by the Z mutation (Glu342Lys) in the serine protease inhibitor α1-antitrypsin (α1AT), which is found in more than 4% of the Northern European population. Homozygotes experience deficiency in the lung concomitantly with a massive accumulation of polymers within hepatocytes, causing their destruction. Recently, it was proposed that Z-α1AT polymerizes by a C-terminal domain swap.

[Endogenous Clostridium septicum panophthalmitis associated with gastrointestinal malignancy].

Endogenous panophthalmitis due to Clostridium septicum (C. septicum) is a rare, but life-threatening condition. There is a known association between infection and malignancy.

Visualization of the eEF2-80S ribosome transition-state complex by cryo-electron microscopy.

In an attempt to understand ribosome-induced GTP hydrolysis on eEF2, we determined a 12.6-A cryo-electron microscopy reconstruction of the eEF2-bound 80S ribosome in the presence of aluminum tetrafluoride and GDP, with aluminum tetrafluoride mimicking the gamma-phosphate during hydrolysis. This is the first visualization of a structure representing a transition-state complex on the ribosome.

The unfolding story of polypeptide release factors.

Two recent cryo-EM reconstructions of the ribosome-bound release factor RF2 reveal an open, tri-lobed shape of RF2, in contrast to the comma-shaped molecule seen in the crystal structure. This indicates that RF2 undergoes a conformational change upon binding to the ribosome. Moreover, RF2 does not seem to be a molecular mimic of tRNA as is the case for elongation factor G.

Bacterial polypeptide release factor RF2 is structurally distinct from eukaryotic eRF1.

Bacterial release factor RF2 promotes termination of protein synthesis, specifically recognizing stop codons UAA or UGA. The crystal structure of Escherichia coli RF2 has been determined to a resolution of 1.8 A.

Molecular design of Mycoplasma hominis Vaa adhesin.

The variable adherence-associated (Vaa) adhesin of the opportunistic human pathogen Mycoplasma hominis is a surface-exposed, membrane-associated protein involved in the attachment of the bacterium to host cells. The molecular masses of recombinant 1 and 2 cassette forms of the protein determined by a light-scattering (LS) method were 23.9 kD and 36.

Structural basis for nucleotide exchange and competition with tRNA in the yeast elongation factor complex eEF1A:eEF1Balpha.

The crystal structure of a complex between the protein biosynthesis elongation factor eEF1A (formerly EF-1alpha) and the catalytic C terminus of its exchange factor, eEF1Balpha (formerly EF-1beta), was determined to 1.67 A resolution. One end of the nucleotide exchange factor is buried between the switch 1 and 2 regions of eEF1A and destroys the binding site for the Mg(2+) ion associated with the nucleotide.

Applications of single-wavelength anomalous dispersion at high and atomic resolution.

Two examples of the application of single-wavelength anomalous dispersion (SAD) in macromolecular structure determination are described, both using the statistical phasing program SHARP. For the holmium-substituted calcium-binding protein psoriasin (22.7 kDa), a set of accurate phases has been obtained to a resolution of 1.

Structural investigations of calcium and zinc binding in proteins.

Metal ions are used in a variety of ways in our cells to regulate, activate, and stabilise specific protein molecules. In this review, we describe some of the regulatory functions of calcium and zinc that have been examined using X-ray crystallographic structural studies of specific proteins. These studies indicate that very precise control of cellular activity can be achieved by exploiting the specific physio-chemical properties of different metal ions.

Macromolecular mimicry.

Some proteins have been shown to mimic the overall shape and structure of nucleic acids. For some of the proteins involved in translating the genetic information into proteins on the ribosome particle, there are indications that such observations of macromolecular mimicry even extend to similarity in interaction with and function on the ribosome. A small number of structural results obtained outside the protein biosynthesis machinery could indicate that the concept of macromolecular mimicry between proteins and nucleic acids is more general.

One year follow-up of astigmatism after 4.0 mm temporal clear corneal and superior scleral incisions.

Purpose: To compare the effect of 2 contemporary sutureless cataract surgery incisions on corneal astigmatism 1 year after surgery.

Setting: Outpatient Clinic, Department of Ophthalmology, Vejle Hospital, Denmark.

Methods: Sixty-nine patients who had cataract surgery in 1997 with a 4.

Structural information for explaining the molecular mechanism of protein biosynthesis.

Protein biosynthesis is controlled by a number of proteins external to the ribosome. Of these, extensive structural investigations have been performed on elongation factor-Tu and elongation factor-G. This now gives a rather complete structural picture of the functional cycle of elongation factor-Tu and especially of the elongation phase of protein biosynthesis.

The crystal structure of Cys-tRNACys-EF-Tu-GDPNP reveals general and specific features in the ternary complex and in tRNA.

Background: . The translation elongation factor EF-Tu in its GTP-bound state forms a ternary complex with any aminoacylated tRNA (aa-tRNA), except initiator tRNA and selenocysteinyl-tRNA. This complex delivers aa-tRNA to the ribosomal A site during the elongation cycle of translation.

Zinc-binding site of an S100 protein revealed. Two crystal structures of Ca2+-bound human psoriasin (S100A7) in the Zn2+-loaded and Zn2+-free states.

The crystal structure of human psoriasin (S100A7) in the native, calcium-bound form has been determined from two crystal forms of the protein crystallized with and without divalent zinc. The overall structures of the dimeric protein closely resemble the previously determined holmium-substituted structure. The structures also reveal a zinc-binding site of the protein, which is formed by three histidines and an aspartate residue.

EF-hands at atomic resolution: the structure of human psoriasin (S100A7) solved by MAD phasing.

Background: The S100 family consists of small acidic proteins, belonging to the EF-hand class of calcium-binding proteins. They are primarily regulatory proteins, involved in cell growth, cell structure regulation and signal transduction. Psoriasin (S100A7) is an 11.

Macromolecular mimicry in protein biosynthesis.

Elongation factor Tu (EF-Tu) is a G-protein which, in its active GTP conformation, protects and carries aminoacylated tRNAs (aa-tRNAs) to the ribosome during protein biosynthesis. EF-Tu consists of three structural domains of which the N-terminal domain consists of two special regions (switch I and switch II) which are structurally dependent on the type of the bound nucleotide. Structural studies of the complete functional cycle of EF-Tu reveal that it undergoes rather spectacular conformational changes when activated from the EF-Tu.

Helix unwinding in the effector region of elongation factor EF-Tu-GDP.

Background: Elongation factor Tu (EF-Tu) in its GTP conformation is a carrier of aminoacylated tRNAs (aa-tRNAs) to the ribosomal A site during protein biosynthesis. The ribosome triggers GTP hydrolysis, resulting in the dissociation of EF-Tu-GDP from the ribosome. The affinity of EF-Tu for other molecules involved in this process, some of which are unknown, is regulated by two regions (Switch I and Switch II) that have different conformations in the GTP and GDP forms.

The GTP binding motif: variations on a theme.

GTP binding proteins (G-proteins) have wide-ranging functions in biology, being involved in cell proliferation, signal transduction, protein synthesis, and protein targeting. Common to their functioning is that they are active in the GTP-bound form and inactive in the GDP-bound form. The protein synthesis elongation factor EF-Tu was the first G-protein whose nucleotide binding domain was solved structurally by X-ray crystallography to yield a structural definition of the GDP-bound form, but a still increasing number of new structures of G-proteins are appearing in the literature, in both GDP and GTP bound forms.

Elongation in bacterial protein biosynthesis.

The past year has brought some notable advances in our understanding of the structure and function of elongation factors (EFs) involved in protein biosynthesis. The structures of the ternary complex of aminoacylated tRNA with EF-Tu.GTP and of the complex EF-Tu.