Plants utilize extracellular vesicles (EVs) to transport small RNAs (sRNAs) into their fungal pathogens and silence fungal virulence-related genes through a phenomenon called “cross-kingdom RNAi.” It remains unknown, however, how sRNAs are selectively loaded into EVs. Here, we identified several RNA-binding proteins (RBPs) in Arabidopsis , including Argonaute 1 (AGO1), RNA helicases (RHs) and Annexins (ANN), which are secreted by exosome-like EVs. AGO1, RH11 and RH37 selectively bind to EV-enriched sRNAs but not non-EV enriched sRNAs, suggesting that they contribute to the selective loading of sRNAs into EVs. Conversely, ANN1 and ANN2 bind to sRNAs non-specifically. The ago1, rh11rh37 and ann1ann2 mutants showed reduced secretion of sRNAs in EVs, demonstrating that these RBPs play an important role in sRNA loading and/or stabilization in EVs. Furthermore, rh11rh37 and ann1ann2 showed increased susceptibility to Botrytis cinerea , supporting that RH11, RH37, ANN1 and ANN2 positively regulate plant immunity against B. cinerea .

SARS-CoV-2 B.1.1.7 and B.1.351 spike variants bind human ACE2 with increased affinity Genomic surveillance efforts have uncovered SARS-CoV-2 variants with mutations in the viral spike glycoprotein, which binds the human angiotensin-converting enzyme 2 (ACE2) receptor to facilitate viral entry. 1 Such variants represent a public health challenge during the COVID-19 pandemic because they increase viral transmission and disease severity. 2 The B.1.351 variant, first identified in South Africa, has three notable mutations in the spike receptorbinding domain (RBD)-namely, K417N, E484K, and N501Y 3 -whereas the B.1.1.7 variant, first identified in the UK, carries the N501Y mutation (appendix pp 2-4). B.1.351 is of particular concern for its potential resistance to antibodies elicited by previous SARS-CoV-2 infection and vaccination. 4 Several mechanisms might account for increased variant transmissibility, such as increased spike protein density, greater furin cleavage accessibility, and enhanced spike protein binding affinity for the ACE2 receptor. 5 To test whether the B.1.351 and B.1.1.7 variants bind ACE2 with

Summary The DNA guanine quadruplexes (G4) play important roles in multiple cellular processes, including DNA replication, transcription and maintenance of genome stability. Here, we showed that Yin Yang-1 (YY1) can bind directly to G4 structures. ChIP-Seq results revealed that YY1 binding sites overlap extensively with G4 structure loci in chromatin. We also observed that YY1’s dimerization and its binding with G4 structures contribute to YY1-mediated long-range DNA looping. Displacement of YY1 from G4 structure sites disrupts substantially the YY1-mediated DNA looping. Moreover, treatment with G4-stabilizing ligands modulates the expression of not only those genes with G4 structures in their promoters, but also those associated with distal G4 structures that are brought to close proximity via YY1-mediated DNA looping. Together, we identified YY1 as a novel DNA G4-binding protein, and revealed that YY1-mediated long-range DNA looping requires its dimerization and occurs, in part, through its recognition of G4 structure.

SARS-CoV2 being highly infectious has been particularly effective in causing widespread infection globally and more variants of SARS-CoV2 are constantly being reported with increased genomic surveillance. In particular, the focus is on mutations of Spike protein, which binds human ACE2 protein enabling SARS-CoV2 entry and infection. Here we present a rapid experimental method leveraging the speed and flexibility of Mircoscale Thermophoresis (MST) to characterize the interaction between Spike Receptor Binding Domain (RBD) and human ACE2 protein. The B.1.351 variant harboring three mutations, (E484K, N501Y, and K417N) binds the ACE2 at nearly five-fold greater affinity than the original SARS-COV-2 RBD. We also find that the B.1.1.7 variant, binds two-fold more tightly to ACE2 than the SARS-COV-2 RBD.

Tumor cells, including cancer stem cells (CSCs) resistant to radio- and chemotherapy, must enhance metabolism to meet the extra energy demands to repair and survive such genotoxic conditions. However, such stress-induced adaptive metabolic alterations, especially in cancer cells that survive radiotherapy, remain unresolved. In this study, we found that CPT1 (Carnitine palmitoyl transferase I) and CPT2 (Carnitine palmitoyl transferase II), a pair of rate-limiting enzymes for mitochondrial fatty acid transportation, play a critical role in increasing fatty acid oxidation (FAO) required for the cellular fuel demands in radioresistant breast cancer cells (RBCs) and radiation-derived breast cancer stem cells (RD-BCSCs). Enhanced CPT1A/CPT2 expression was detected in the recurrent human breast cancers and associated with a worse prognosis in breast cancer patients. Blocking FAO via a FAO inhibitor or by CRISPR-mediated CPT1A/CPT2 gene deficiency inhibited radiation-induced ERK activation and aggressive growth and radioresistance of RBCs and RD-BCSCs. These results revealed that switching to FAO contributes to radiation-induced mitochondrial energy metabolism, and CPT1A/CPT2 is a potential metabolic target in cancer radiotherapy.