It has been reported that SARS-CoV-2 may use ACE2 as a receptor to gain entry into human cells, in a way similar to that of SARS-CoV. Analyzing the distribution and expression level of ACE2 may therefore help reveal underlying mechanisms of viral susceptibility and post-infection modulation. In this study, we utilized previously uploaded information on ACE2 expression in various conditions including SARS-CoA to evaluate the role of ACE2 in SARS-CoV and extrapolate that to COVID-19. We found that the expression of ACE2 in healthy populations and patients with underlying diseases was not significantly different. However, based on the elevated expression of ACE2 in cigarette smokers, we speculate that long-term smoking may be a risk factor for COVID-19. Analysis of ACE2 in SARS-CoV infected cells suggests that ACE2 is not only a receptor but is also involved in post-infection regulation, including immune response, cytokine secretion, and viral genome replication. Moreover, we constructed Protein-protein interaction (PPI) networks and identified hub genes in viral activity and cytokine secretion. Our findings may help clinicians and researchers gain more insight into the pathogenesis of SARS-CoV-2 and design therapeutic strategies for COVID-19.

Hormonal crosstalk is central for tailoring plant responses to the nature of challenges encountered. The role of antagonism between the two major defense hormones, salicylic acid (SA) and jasmonic acid (JA), and modulation of this interplay by ethylene (ET) in favor of JA signaling pathway in plant stress responses is well recognized, but the underlying mechanism is not fully understood. Here, we show the opposing function of two transcription factors, ethylene insensitive3 (EIN3) and EIN3-Like1 (EIL1), in SA-mediated suppression and JA-mediated activation of PLANT DEFENSIN1.2 (PDF1.2). This functional duality is mediated via their effect on protein, not transcript levels of the PDF1.2 transcriptional activator octadecanoid-responsive arabidopsis59 (ORA59). Specifically, JA induces ORA59 protein levels independently of EIN3/EIL1, whereas SA reduces the protein levels dependently of EIN3/EIL1. Co-infiltration assays revealed nuclear co-localization of ORA59 and EIN3, and split-luciferase together with yeast-two-hybrid assays established their physical interaction. The functional ramification of the physical interaction is EIN3-dependent degradation of ORA59 by the 26S proteasome. These findings allude to SA-responsive reduction of ORA59 levels mediated by EIN3 binding to and targeting of ORA59 for degradation, thus nominating ORA59 pool as a coordination node for the antagonistic function of ET/JA and SA.

Salinity, which is one of the most common abiotic stresses, may severely affect plant productivity and quality. Although plant lectins are thought to play important roles in plant defense signaling during pathogen attack, little is known about the contribution of plant lectins to stress resistance. We cloned and functionally characterized a rice jacalin-related mannose-binding lectin gene, OsJRL, from rice 'Nipponbare'. We analyzed the expression patterns of OsJRL under various stress conditions in rice. Furthermore, we overexpressed OsJRL in Escherichia coli and rice. The cDNA of OsJRL contained a 438 bp open reading frame, which encodes a polypeptide of 145 amino acids. OsJRL was localized in the nucleus and cytoplasm. Real time PCR analyses revealed that OsJRL expression showed tissue specificity in rice and was upregulated under diverse stresses, namely salt, drought, cold, heat and abscisic acid treatments. Overexpression of OsJRL in E. coli enhanced cell viability and dramatically improved tolerance of high salinity. Overexpression of OsJRL in rice also enhanced salinity tolerance and increased the expression levels of a number of stress-related genes, including three LEA (late embryogenesis abundant proteins) genes (OsLEA19a, OsLEA23 and OsLEA24), three Na transporter genes (OsHKT1;3, OsHKT1;4 and OsHKT1;5) and two DREB genes (OsDREB1A and OsDREB2B). Based on these results, we suggest that OsJRL plays an important role in cell protection and stress signal transduction.

The aim of metalloproteomics is to identify and characterize putative metal-binding proteins and metal-binding motifs. In this study, we performed a systematical metalloproteomic analysis on Streptococcus pneumoniae through the combined use of efficient immobilized metal affinity chromatography enrichment and high-accuracy linear ion trap-Orbitrap MS to identify metal-binding proteins and metal-binding peptides. In total, 232 and 166 putative metal-binding proteins were respectively isolated by Cu- and Zn-immobilized metal affinity chromatography columns, in which 133 proteins were present in both preparations. The putative metalloproteins are mainly involved in protein, nucleotide and carbon metabolisms, oxidation and cell cycle regulation. Based on the sequence of the putative Cu- and Zn-binding peptides, putative Cu-binding motifs were identified: H(X)mH (m=0-11), C(X)(2) C, C(X)nH (n=2-4, 6, 9), H(X)iM (i=0-10) and M(X)tM (t=8 or 12), while putative Zn-binding motifs were identified as follows: H(X)mH (m=1-12), H(X)iM (i=0-12), M(X)tM (t=0, 3 and 4), C(X)nH (n=1, 2, 7, 10 and 11). Equilibrium dialysis and inductively coupled plasma-MS experiments confirmed that the artificially synthesized peptides harboring differential identified metal-binding motifs interacted directly with the metal ions. The metalloproteomic study presented here suggests that the comparably large size and diverse functions of the S. pneumoniae metalloproteome may play important roles in various biological processes and thus contribute to the bacterial pathologies.