No abstract available

No abstract available

JmjC domain containing protein 14 (JMJ14) is an H3K4-specific histone demethylase that plays important roles in RNA-mediated gene silencing and flowering time regulation in Arabidopsis. However, how JMJ14 is recruited to its target genes remains unclear. Here, we show that the C-terminal FYRN and FYRC domains of JMJ14 are required for RNA silencing and flowering time regulation. Chromatin binding of JMJ14 is lost upon deletion of its FYRN and FYRC domains, and H3K4me3 is increased. FYRN and FYRC domains interact with a pair of NAC domain containing transcription factors, NAC050 and NAC052. Genome-wide ChIP analysis revealed that JMJ14 and NAC050/052 share a set of common target genes with CTTGNNNNNCAAG consensus sequences. Mutations in either NAC052 or NAC050 impair RNA-mediated gene silencing. Together, our findings demonstrate an important role of FYRN and FYRC domains in targeting JMJ14 through direct interaction with NAC050/052 proteins, which reveals a novel mechanism of histone demethylase recruitment.

The emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants of concern, including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529) has aroused concerns over their increased infectivity and transmissibility, as well as decreased sensitivity to SARS-CoV-2-neutralizing antibodies (NAbs) and the current coronavirus disease 2019 (COVID-19) vaccines. Such exigencies call for the development of pan-sarbecovirus vaccines or inhibitors to combat the circulating SARS-CoV-2 NAb-escape variants and other sarbecoviruses. In this study, we isolated a broadly NAb against sarbecoviruses named GW01 from a donor who recovered from COVID-19. Cryo-EM structure and competition assay revealed that GW01 targets a highly conserved epitope in a wide spectrum of different sarbecoviruses. However, we found that GW01, the well-known sarbecovirus NAb S309, and the potent SARS-CoV-2 NAbs CC12.1 and REGN10989 only neutralize about 90% of the 56 tested currently circulating variants of SARS-CoV-2 including Omicron. Therefore, to improve efficacy, we engineered an IgG-like bispecific antibody GW01-REGN10989 (G9) consisting of single-chain antibody fragments (scFv) of GW01 and REGN10989. We found that G9 could neutralize 100% of NAb-escape mutants (23 out of 23), including Omicron variant, with a geometric mean (GM) 50% inhibitory concentration of 8.8 ng/mL. G9 showed prophylactic and therapeutic effects against SARS-CoV-2 infection of both the lung and brain in hACE2-transgenic mice. Site-directed mutagenesis analyses revealed that GW01 and REGN10989 bind to the receptor-binding domain in different epitopes and from different directions. Since G9 targets the epitopes for both GW01 and REGN10989, it was effective against variants with resistance to GW01 or REGN10989 alone and other NAb-escape variants. Therefore, this novel bispecific antibody, G9, is a strong candidate for the treatment and prevention of infection by SARS-CoV-2, NAb-escape variants, and other sarbecoviruses that may cause future emerging or re-emerging coronavirus diseases.

The pandemic of COVID-19 caused by SARS-CoV-2 continues to spread around the world. Mutant strains of SARS-CoV-2 are constantly emerging. At present, Omicron variants have become mainstream. In this work, we carried out a systematic and comprehensive analysis of the reported spike protein antibodies, counting the epitopes and genotypes of these antibodies. We further comprehensively analyzed the impact of Omicron mutations on antibody epitopes and classified these antibodies according to their binding patterns. We found that the epitopes of the H-RBD class antibodies were significantly less affected by Omicron mutations than other classes. Binding and virus neutralization experiments showed that such antibodies could effectively inhibit the immune escape of Omicron. Cryo-EM results showed that this class of antibodies utilized a conserved mechanism to neutralize SARS-CoV-2. Our results greatly help us deeply understand the impact of Omicron mutations. Meanwhile, it also provides guidance and insights for developing Omicron antibodies and vaccines.

The human SLC26 transporter family exhibits various transport characteristics, and family member SLC26A9 performs multiple roles, including acting as Cl-/HCO3- exchangers, Cl- channels, and Na+ transporters. Some mutations of SLC26A9 are correlated with abnormalities in respiration and digestion systems. As a potential target colocalizing with CFTR in cystic fibrosis patients, SLC26A9 is of great value in drug development. Here, we present a cryo-EM structure of the human SLC26A9 dimer at 2.6 Å resolution. A segment at the C-terminal end is bound to the entry of the intracellular vestibule of the putative transport pathway, which has been proven by electrophysiological experiments to be a gating modulator. Multiple chloride and sodium ions are resolved in the high-resolution structure, identifying novel ion-binding pockets for the first time. Together, our structure takes important steps in elucidating the structural features and regulatory mechanism of SLC26A9, with potential significance in the treatment of cystic fibrosis.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) continue to wreak havoc across the globe. Higher transmissibility and immunologic resistance of VOCs bring unprecedented challenges to epidemic extinguishment. Here we describe a monoclonal antibody, 2G1, that neutralizes all current VOCs and has surprising tolerance to mutations adjacent to or within its interaction epitope. Cryo-electron microscopy structure showed that 2G1 bound to the tip of receptor binding domain (RBD) of spike protein with small contact interface but strong hydrophobic effect, which resulted in nanomolar to sub-nanomolar affinities to spike proteins. The epitope of 2G1 on RBD partially overlaps with angiotensin converting enzyme 2 (ACE2) interface, which enables 2G1 to block interaction between RBD and ACE2. The narrow binding epitope but high affinity bestow outstanding therapeutic efficacy upon 2G1 that neutralized VOCs with sub-nanomolar half maximal inhibitory concentration in vitro. In SARS-CoV-2, Beta or Delta variant-challenged transgenic mice and rhesus macaque models, 2G1 protected animals from clinical illness and eliminated viral burden, without serious impact to animal safety. Mutagenesis experiments suggest that 2G1 is potentially capable of dealing with emerging SARS-CoV-2 variants in the future. This report characterized the therapeutic antibodies specific to the tip of spike against SARS-CoV-2 variants and highlights the potential clinical applications as well as for developing vaccine and cocktail therapy.