Ezrin interacts with the SARS coronavirus spike protein and restrains infection at the entry stage

© 2012 Millet et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: Entry of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) and its envelope fusion with host cell membrane are controlled by a series of complex molecular mechanisms, largely dependent on the viral envelope glycoprotein Spike (S). There are still many unknowns on the implication of cellular factors that regulate the entry process. Methodology/Principal Findings: We performed a yeast two-hybrid screen using as bait the carboxy-terminal endodomain of S, which faces the cytosol during and after opening of the fusion pore at early stages of the virus life cycle. Here we show that the ezrin membrane-actin linker interacts with S endodomain through the F1 lobe of its FERM domain and that both the eight carboxy-terminal amino-acids and a membrane-proximal cysteine cluster of S endodomain are important for this interaction in vitro. Interestingly, we found that ezrin is present at the site of entry of S-pseudotyped lentiviral particles in Vero E6 cells. Targeting ezrin function by small interfering RNA increased S-mediated entry of pseudotyped particles in epithelial cells. Furthermore, deletion of the eight carboxy-terminal amino acids of S enhanced S-pseudotyped particles infection. Expression of the ezrin dominant negative FERM domain enhanced cell susceptibility to infection by SARS-CoV and S pseudotyped particles and potentiated S-dependent membrane fusion. Conclusions/Significance: Ezrin interacts with SARS-CoV S endodomain and limits virus entry and fusion. Our data present a novel mechanism involving a cellular factor in the regulation of S-dependent early events of infection.This work was supported by the Research Grant Council of Hong Kong (RGC#760208)and the RESPARI project of the International Network of Pasteur Institutes

Intracellular Targeting Signals Contribute to Localization of Coronavirus Spike Proteins near the Virus Assembly Site

Coronavirus budding at the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) requires accumulation of the viral envelope proteins at this point in the secretory pathway. Here we demonstrate that the spike (S) protein from the group 3 coronavirus infectious bronchitis virus (IBV) contains a canonical dilysine endoplasmic reticulum retrieval signal (-KKXX-COOH) in its cytoplasmic tail. This signal can retain a chimeric reporter protein in the ERGIC and when mutated allows transport of the full-length S protein as well as the chimera to the plasma membrane. Interestingly, the IBV S protein also contains a tyrosine-based endocytosis signal in its cytoplasmic tail, suggesting that any S protein that escapes the ERGIC will be rapidly endocytosed when it reaches the plasma membrane. We also identified a novel dibasic motif (-KXHXX-COOH) in the cytoplasmic tails of S proteins from group 1 coronaviruses and from the newly identified coronavirus implicated in severe acute respiratory syndrome. This dibasic motif also retained a reporter protein in the ERGIC, similar to the dilysine motif in IBV S. The cytoplasmic tails of S proteins from group 2 coronaviruses lack an intracellular localization signal. The inherent differences in S-protein trafficking could point to interesting variations in pathogenesis of coronaviruses, since increased levels of surface S protein could promote syncytium formation and direct cell-to-cell spread of the infection

#NoStudentsLeftBehind: The Role of Digital Inclusion in the Academic Performance of Senior High School Students Amid the Pandemic

As society continually progresses in the 21st century, there is evident advancement in the utilization of digital devices and the internet. With this, digital inclusion, or an individual’s ability to use and access information and communications technology (ICT), is particularly relevant in the present day. Furthermore, the COVID-19 pandemic has only exacerbated the need for adequate digital inclusion levels among students. This paper describes the relationship between the digital inclusion levels and the academic performance of senior high school students during the pandemic, and determines the sociodemographic and socioeconomic characteristics that influence both digital inclusion and academic performance. Using a sample of 203 senior high school students residing in Metro Manila, data was collected by means of an online survey questionnaire utilizing a 5-point Likert scale conducted through Google Forms. The data obtained were viewed and analyzed through a descriptive-quantitative research approach, mainly utilizing inferential statistics, to exhaust and determine the correlation between the primary variables of the study. The findings indicate that there is a significant relationship between digital inclusion levels and academic performance with all three digital inclusion levels expressing significant correlations. Moreover, data present that digital access has the largest effect on the academic performance of the students during the pandemic. Overall, the study suggests that the sociodemographic characteristics, socioeconomic characteristics, and digital inclusion levels all significantly contribute to the academic performance of Metro Manila senior high school students amid the COVID-19 pandemic

Traffic COPs: rules of detection

EMBO J (2013) 32:11, 926–937 doi:10.1038/emboj.2013.41; published online 03122013 Dev Cell (2012) 23: 1255–62 doi:10.1016/j.devcel.2012.10.017; published online 12112012 How specific cargo recognition by coat proteins is achieved and how this recognition event may regulate vesicle formation are still under investigation. In two recent papers by the Owen and Goldberg labs, the binding mode of dilysine motifs to the coatomer of the COPI coat has been analysed. Collectively, their findings suggest that the dilysine motif containing cargo proteins may stabilize coat complexes on membranes and enhance the chance for coat polymerization and vesicle budding