The receptor-binding domain (RBD) of the severe acute respiratory syndrome coronavirus 2s pike (S) protein playsacentral role in mediating the first step of virus infection to cause disease:v irus binding to angiotensin-converting enzyme 2( ACE2) receptors on human host cells.T herefore, S/RBD is an ideal target for blocking and neutralization therapies to prevent and treat coronavirus disease 2019 (COVID-19). Using at arget-based selection approach, we developed oligonucleotide aptamers containing ac onserved sequence motif that specifically targets S/RBD.S ynthetic aptamers had high binding affinity for S/RBD-coated virus mimics (K D % 7nM) and also blocked interaction of S/RBD with ACE2 receptors (IC 50 % 5nM). Importantly,a ptamers were able to neutralizeSprotein-expressing viral particles and prevent host cell infection, suggesting apromising COVID-19 therapys trategy.

The receptor-binding domain (RBD) of the severe acute respiratory syndrome coronavirus 2s pike (S) protein playsacentral role in mediating the first step of virus infection to cause disease:v irus binding to angiotensin-converting enzyme 2( ACE2) receptors on human host cells.T herefore, S/RBD is an ideal target for blocking and neutralization therapies to prevent and treat coronavirus disease 2019 (COVID-19). Using at arget-based selection approach, we developed oligonucleotide aptamers containing ac onserved sequence motif that specifically targets S/RBD.S ynthetic aptamers had high binding affinity for S/RBD-coated virus mimics (K D % 7nM) and also blocked interaction of S/RBD with ACE2 receptors (IC 50 % 5nM). Importantly,a ptamers were able to neutralizeSprotein-expressing viral particles and prevent host cell infection, suggesting apromising COVID-19 therapys trategy.

Ribonucleotide reductase (RNR) is an essential enzyme found in all organisms. The function of RNR is to catalyze the conversion of nucleotides to deoxynucleotides. RNRs rely on metallocofactors to oxidize a conserved cysteine in the active site of the enzyme into a thiyl radical, which then initiates nucleotide reduction. The proteins required for MnIII2–Y• cluster formation in class Ib RNRs are NrdF (β-subunit) and NrdI (flavodoxin). An oxidant is channeled from the FMN cofactor in NrdI to the dimanganese center in NrdF, where it oxidizes the dimanganese center and a tyrosyl radical (Y•) is formed. Both Streptococcus sanguinis and Escherichia coli MnII2–NrdF structures have a constriction in the channel immediately above the metal site. In E. coli, the constriction is formed by the side chain of S159, whereas in the S. sanguinis system it involves T158. This serine-to-threonine substitution was investigated using S. sanguinis and Streptococcus pneumoniae class Ib RNRs but it is also present in other pathogenic streptococci. Using stopped-flow kinetics, we investigate the role of this substitution in the mechanism of MnIII2–Y• cluster formation. In addition to different kinetics observed in the studied streptococci, we found that affinity constants of NrdF for MnII and FeII are about 1 µM and the previously reported preference for MnII could not be explained by affinity only.

Breast cancer (BC) is the most common type of cancer diagnosed in women. Among female cancer deaths, BC is the second leading cause of death worldwide. For estrogen receptor-positive (ER-positive) breast cancers, endocrine therapy is an effective therapeutic approach. However, in many cases, an ER-positive tumor becomes unresponsive to endocrine therapy, and tumor regrowth occurs after treatment. While some genetic mutations contribute to resistance in some patients, the underlying causes of resistance to endocrine therapy are mostly undetermined. In this study, we utilized a recently developed statistical approach to investigate the dynamic behavior of gene expression during the development of endocrine resistance and identified a novel group of genes whose time course expression significantly change during cell modelling of endocrine resistant BC development. Expression of a subset of these genes was also differentially expressed in microarray analysis of endocrine-resistant and endocrine-sensitive tumor samples. Surprisingly, a subset of those genes was also differentially genes expressed in triple-negative breast cancer (TNBC) as compared with ER-positive BC. The findings suggest shared genetic mechanisms may underlie the development of endocrine resistant BC and TNBC. Our findings identify 34 novel genes for further study as potential therapeutic targets for treatment of endocrine-resistant BC and TNBC.