Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) poses a public health threat for which preventive and therapeutic agents are urgently needed. Neutralizing antibodies are a key class of therapeutics which may bridge widespread vaccination campaigns and offer a treatment solution in populations less responsive to vaccination. Herein, we report that high-throughput microfluidic screening of antigen-specific B-cells led to the identification of LY-CoV555 (also known as bamlanivimab), a potent anti-spike neutralizing antibody from a hospitalized, convalescent patient with coronavirus disease 2019 (COVID-19). Biochemical, structural, and functional characterization of LY-CoV555 revealed high-affinity binding to the receptor-binding domain, angiotensin converting enzyme 2 binding inhibition, and potent neutralizing activity. A pharmacokinetic study of LY-CoV555 conducted in cynomolgus monkeys demonstrated a mean half-life of 13 days, and clearance of 0.22 mL/hr/kg, consistent with a typical human therapeutic antibody. In a rhesus macaque challenge model, prophylactic doses as low as 2.5 mg/kg reduced viral replication in the upper and lower respiratory tract in samples collected through study Day 6 following viral inoculation. This antibody has entered clinical testing and is being evaluated across a spectrum of COVID-19 indications, including prevention and treatment.

Cell-free expression is emerging as a prime method for the rapid production of preparative quantities of high-quality membrane protein samples. The technology facilitates easy access to large numbers of proteins that have been extremely difficult to obtain. Most frequently used are cell-free systems based on extracts of Escherichia coli cells, and the reaction procedures are reliable and efficient. This protocol describes the preparation of all essential reaction components such as the E. coli cell extract, T7 RNA polymerase, DNA templates as well as the individual stock solutions. The setups of expression reactions in analytical and preparative scales, including a variety of reaction designs, are illustrated. We provide detailed reaction schemes that allow the preparation of milligram amounts of functionally folded membrane proteins of prokaryotic and eukaryotic origin in less than 24 h.

SARS-CoV-2 poses a public health threat for which therapeutic agents are urgently needed. Herein, we report that high-throughput microfluidic screening of antigen-specific B-cells led to the identification of LY-CoV555, a potent anti-spike neutralizing antibody from a convalescent COVID-19 patient. Biochemical, structural, and functional characterization revealed high-affinity binding to the receptor-binding domain, ACE2 binding inhibition, and potent neutralizing activity. In a rhesus macaque challenge model, prophylaxis doses as low as 2.5 mg/kg reduced viral replication in the upper and lower respiratory tract. These data demonstrate that high-throughput screening can lead to the identification of a potent antiviral antibody that protects against SARS-CoV-2 infection.

Hypoxia that develops in solid tumors stabilizes the hypoxiainducible factor-1A (HIF-1A) subunit of the HIF-1 transcription factor, leading to up-regulation of dozens of hypoxia-regulated genes that increase glycolysis and oxygen delivery. HIF-1A and its downstream target gene CA9 have both been used as surrogate hypoxia markers, and, in general, high expression predicts for a poor response to treatment. Combinations of hypoxia markers offer the opportunity to measure changes in tumor oxygenation that may be relevant to tumor response to treatment. We compared the degree of colocalization of two endogenous markers for hypoxia, HIF-1A and carbonic anhydrase IX (CAIX), with a chemical marker for hypoxia, pimonidazole. Unexpectedly, expression of HIF-1A was reduced in the most hypoxic regions that border necrosis in xenograft tumors composed of SiHa cervical carcinoma, WiDr colon carcinoma, or M006 astrocytoma cells. Similar results were obtained for samples from three cervical cancer biopsies. However, CAIX was present in these perinecrotic cells that were also capable of metabolizing and binding a chemical marker for hypoxia, pimonidazole. In vitro experiments using tumor cells and tumor cubes incubated under anoxic conditions indicated that nutrient deprivation seems to be largely responsible for the lack of HIF-1A expression in perinecrotic regions. The half-life of CAIX was sufficiently long that, once formed, it remained for days in the absence of continued HIF-1A expression. These results have implications for the use of HIF-1A as an indicator of tumor hypoxia and aggressiveness as well as development of hypoxia-directed antitumor therapies based on the expression of HIF-1A. (Cancer Res 2005; 65(16): 7259-66)

The γ-secretase complex has a decisive role in the development of Alzheimer's disease, in that it cleaves a precursor to create the amyloid β peptide whose aggregates form the senile plaques encountered in the brains of patients. Γ-secretase is a member of the intramembrane-cleaving proteases which process their transmembrane substrates within the bilayer. Many of the mutations encountered in early onset familial Alzheimer's disease are linked to presenilin 1, the catalytic component of γ-secretase, whose active form requires its endoproteolytic cleavage into N-terminal and C-terminal fragments. Although there is general agreement regarding the topology of the N-terminal fragment, studies of the C-terminal fragment have yielded ambiguous and contradictory results that may be difficult to reconcile in the absence of structural information. Here we present the first structure of the C-terminal fragment of human presenilin 1, as obtained from NMR studies in SDS micelles. The structure reveals a topology where the membrane is likely traversed three times in accordance with the more generally accepted nine transmembrane domain model of presenilin 1, but contains unique structural features adapted to accommodate the unusual intramembrane catalysis. These include a putative half-membrane-spanning helix N-terminally harboring the catalytic aspartate, a severely kinked helical structure toward the C terminus as well as a soluble helix in the assumed-to-be unstructured N-terminal loop.cell-free protein expression | gamma secretase | intramembrane proteolysis | membrane protein structure A lzheimer's disease is the most common form of dementia and affects more than 25 million people worldwide. The most characteristic histological feature of Alzheimer's disease is the presence of long, insoluble amyloid fibrils composed of amyloid β (Aβ) peptide which, either alone or as reservoirs for soluble Aβ oligomers (1, 2), appear to be the primary species responsible for the massive neuronal injury presented in patients. Aβ generation is categorized under an unusual physiological phenomenon termed regulated intramembrane proteolysis. Here, the amyloid precursor protein first sheds its ectodomain mediated by β-secretase. The remaining membrane-bound C-terminal fragment is subsequently processed at a γ-cleavage site by the γ-secretase complex, a multisubunit protease whose minimal essential components include presenilin 1 (PS1) or presenilin-2 (PS2), anterior pharynx-defective, nicastrin, and presenilin enhancer 2 (3). The pathological relevance of this final step lies in the observation that γ-cleavage is variable and can occur after three distinct positions, 38, 40, and 42, whose selection influences the self-aggregating potential of the secreted Aβ peptide. Aβ42, although the minor species, appears to show the strongest potency for oligomerization and represents the majority of Aβ in amyloid plaques (4). Over 150 familial Alzheimer's disease associated mutations (www.molgen.ua.ac.be/ADMutations) have been linked to PS1, the catalyt...