Proteomic Analysis and Virulence Assessment of Granulicatella adiacens Secretome

Abstract

Despite reports on the occurrence of Granulicatella adiacens in infective endocarditis, few mechanistic studies on its virulence characteristics or pathogenicity are available. Proteins secreted by this species may act as determinants of host-microbe interaction and play a role in virulence. Our aim in this study was to investigate and functionally characterize the secretome of G. adiacens . Proteins in the secretome preparation were digested by trypsin and applied to nanoLC-ESI-MS/MS. By using a combined mass spectrometry and bioinformatics approach, we identified 101 proteins. Bioinformatics tools predicting subcellular localization revealed that 18 of the secreted proteins possessed signal sequence. More than 20% of the secretome proteins were putative virulence proteins including serine protease, superoxide dismutase, aminopeptidase, molecular chaperone DnaK, and thioredoxin. Ribosomal proteins, molecular chaperones, and glycolytic enzymes, together known as “moonlighting proteins,” comprised fifth of the secretome proteins. By Gene Ontology analysis, more than 60 proteins of the secretome were grouped in biological processes or molecular functions. KEGG pathway analysis disclosed that the secretome consisted of enzymes involved in biosynthesis of antibiotics. Cytokine profiling revealed that secreted proteins stimulated key cytokines, such as IL-1β, MCP-1, TNF-α, and RANTES from human PBMCs. In summary, the results from the current investigation of the G. adiacens secretome provide a basis for understanding possible pathogenic mechanisms of G. adiacens .

Characterization and Diversity Analysis of the Extracellular Proteases of Thermophilic Anoxybacillus caldiproteolyticus 1A02591 From Deep-Sea Hydrothermal Vent Sediment

“…In addition, we noticed that among the 12 secreted proteases, only 5 have a predicted signal peptide, that is, 1 M4 protease, 1 S8 protease, 1 S11 protease, 1 C40 protease, and 1 M23 protease, which are likely secreted by signal peptide-mediated translocation. The other 7 secreted proteases without a predicted signal peptide might be secreted outside the cell via other secretion systems, such as the twin-arginine transport pathway, or a non-classical secretory system ( Karched et al, 2019 ). As shown in Table 3 , there are 10 putative proteases with a predicted signal peptide in strain 1A02591.…”

Internal jugular vein thrombosis associated withGranulicatella adiacens

“… 2 G. adiacens is a type of nutritionally variant streptococcus found as part of the normal microbiota in the oral cavity and is an uncommon source of infection. 3 They are found in dental plaque and can cause endodontic infection and dental abscesses. However, they can also cause more serious bloodstream infections including endocarditis or device infections.…”

Phosphorylation of Extracellular Proteins in Acinetobacter baumannii in Sessile Mode of Growth

“…Initial bioinformatic analyses indicated that the majority of the modified proteins were predicted to be cytoplasmic, with only 3% predicted to be secreted (Supplementary Tables 7, 8). However, it is well known that many predicted cytoplasmic proteins can also be secreted, e.g., DnaK (Karched et al, 2019), EF-Tu (Chiu et al, 2017), and GroEL (Jeffery C.J., 2018). Such multifunctional proteins are also known as moonlighting proteins and may be involved in adhesion to the host or in microbial pathogenesis (Hagemann et al, 2017;Harvey et al, 2019;Jeffery C.J., 2019;N'Diaye et al, 2019).…”