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In December 2019, SARS-CoV-2 emerged causing the COVID-19 pandemic. SARS-CoV, the agent responsible for the 2003 SARS outbreak, utilizes ACE2 and TMPRSS2 host molecules for viral entry. ACE2 and TMPRSS2 have recently been implicated in SARS-CoV-2 viral infection. Additional host molecules including ADAM17, cathepsin L, CD147, and GRP78 may also function as receptors for SARS-CoV-2.To determine the expression and in situ localization of candidate SARS-CoV-2 receptors in the respiratory mucosa, we analyzed gene expression datasets from airway epithelial cells of 515 healthy subjects, gene promoter activity analysis using the FANTOM5 dataset containing 120 distinct sample types, single cell RNA sequencing (scRNAseq) of 10 healthy subjects, immunoblots on multiple airway epithelial cell types, and immunohistochemistry on 98 human lung samples.We demonstrate absent to low ACE2 promoter activity in a variety of lung epithelial cell samples and low ACE2 gene expression in both microarray and scRNAseq datasets of epithelial cell populations. Consistent with gene expression, rare ACE2 protein expression was observed in the airway epithelium and alveoli of human lung. We present confirmatory evidence for the presence of TMPRSS2, CD147, and GRP78 protein in vitro in airway epithelial cells and confirm broad in situ protein expression of CD147 in the respiratory mucosa.Collectively, our data suggest the presence of a mechanism dynamically regulating ACE2 expression in human lung, perhaps in periods of SARS-CoV-2 infection, and also suggest that alternate receptors for SARS-CoV-2 exist to facilitate initial host cell infection.

In December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged, causing the coronavirus disease 2019 (COVID-19) pandemic. SARS-CoV, the agent responsible for the 2003 SARS outbreak, utilises angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) host molecules for viral entry. ACE2 and TMPRSS2 have recently been implicated in SARS-CoV-2 viral infection. Additional host molecules including ADAM17, cathepsin L, CD147 and GRP78 may also function as receptors for SARS-CoV-2.To determine the expression and in situ localisation of candidate SARS-CoV-2 receptors in the respiratory mucosa, we analysed gene expression datasets from airway epithelial cells of 515 healthy subjects, gene promoter activity analysis using the FANTOM5 dataset containing 120 distinct sample types, single cell RNA sequencing (scRNAseq) of 10 healthy subjects, proteomic datasets, immunoblots on multiple airway epithelial cell types, and immunohistochemistry on 98 human lung samples.We demonstrate absent to low ACE2 promoter activity in a variety of lung epithelial cell samples and low ACE2 gene expression in both microarray and scRNAseq datasets of epithelial cell populations. Consistent with gene expression, rare ACE2 protein expression was observed in the airway epithelium and alveoli of human lung, confirmed with proteomics. We present confirmatory evidence for the presence of TMPRSS2, CD147 and GRP78 protein in vitro in airway epithelial cells and confirm broad in situ protein expression of CD147 and GRP78 in the respiratory mucosa.Collectively, our data suggest the presence of a mechanism dynamically regulating ACE2 expression in human lung, perhaps in periods of SARS-CoV-2 infection, and also suggest that alternative receptors for SARS-CoV-2 exist to facilitate initial host cell infection.

The influences of two strains of Pseudomonas putida UW4, a plant growth-promoting bacterium (PGPB) on the shoot and root proteomic profiles of Brassica napus (canola) were examined under salinity stress using two-dimensional difference gel electrophoresis. The two strains (wild-type UW4 and an AcdS minus mutant strain) differ in the availability of a functional 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, a bacterial protein known to play a role in host plant's stress responses. In total, ninety protein spots (representing 76 different proteins) with significantly altered expression levels in the presence of salt and/or bacteria were identified by mass spectrometry. Many of the identified proteins are involved in photosynthesis, anti-oxidative processes, transportation across membranes, and pathogenesis-related responses. The effects of salt and bacteria on the canola proteome were shown to be quite diverse, with salinity stress causing more dramatic plant protein expression changes than bacteria. In addition, bacteria were demonstrated to moderate some of the salt effects on plant protein differential expression. This work contributes to the understanding of how plant protein expression is affected by various environmental signals.

A proteome reference map containing 326 2-D gel spots representing 275 different proteins was constructed for the plant growth-promoting bacterium Pseudomonas putida UW4. Protein identifications were obtained using Q-TOF MS/MS spectra matching to homologous proteins from other Pseudomonas strains and confirmed by PMF analysis. This data set is accessible at http://world-2dpage.expasy.org/repository/ and will aid in further characterization of Pseudomonas strains and interactions of plant growth-promoting bacterium with the plant rhizosphere environment.