Project description:Most bacteria are in fierce competition with other species for limited nutrients. Some bacteria can kill nearby cells by secreting bacteriocins, a diverse group of proteinaceous antimicrobials. However, bacteriocins are typically freely diffusible, and so of little value to planktonic cells in aqueous environments. Here, we identify an atypical two-protein bacteriocin in the gamma-proteobacterium Caulobacter crescentus that is retained on the surface of producer cells where it mediates cell contact-dependent killing. The bacteriocin-like proteins CdzC and CdzD harbor glycine-zipper motifs, often found in amyloids, and CdzC forms large, insoluble aggregates on the surface of producer cells. These aggregates can drive contact-dependent killing of other organisms, or Caulobacter cells not producing the CdzIE immunity protein. The Cdz system uses a type I secretion system and is unrelated to previously described contact-dependent inhibition systems. However, Cdz-like systems are found in many bacteria, suggesting that this form of contact-dependent inhibition is common.
2017-05-03 | GSE96582 | GEO
Project description:RNA-seq of cheese starter cultures
Project description:Bacteriocins are natural antimicrobial peptides produced by a bacterium to kill closely related competitors. Streptococcus gallolyticus subsp. gallolyticus (Sgg) UCN34 produces a two-component bacteriocin named gallocin to colonize the gut by killing resident enterococci. In the present work, we investigated how gallocin was regulated by deleting individually three genes present in the locus and encoding potentially an inducing peptide (gsp), a histidine kinase (ghk) and a LytTR-containing response regulator (grr). Comparative transcriptional analyses of these three mutants as compared to the WT UCN34 showed that this 3- component regulatory system induces the transcription of the whole gallocin locus encoding gallocin but also five others putative bacteriocins and genes necessary for bacteriocins biosynthesis and secretion. Beside gallocin locus, only two other pairs of genes were coordinately induced in Sgg genome, encoding an ABC transporter and hypothetical proteins. We conclude that this regulatory system appears highly specialized in bacteriocins induction in Sgg UCN34.
Project description:Backgroung: Antibody and cell-based immunotherapies, e.g., antibody-drug-conjugates and CAR-T cells, targeted at cell-surface proteins, currently revolutionize clinical oncology. However, target selection warrants a better understanding of the surface-endocytome and how it is modulated by the tumor microenvironment. Here, we unravel the surface-endocytome landscape and its remodeling by hypoxia in primary cultures from glioblastoma (GBM) patients that currently lack targeted therapies. Methods. We employed a comprehensive approach for global and dynamic mapping of surfaceome and endocytosed (endocytome) proteins in primary GBM cultures at normoxia or hypoxia. Selected target candidates were validated by immunofluorescence analyses in patient tumor sections, spheroids, and 2D cultures, and were finally confronted by ADC cytotoxicity studies. Results: We reveal a heterogeneous surface-endocytome profile across GBM cultures from three patients representing different transcriptional subtypes. CD44 emerged as a commonly abundant surfaceome antigen across GBM cultures, and we established a direct correlation between CD44 endocytic activity and ADC cytotoxicity. We elucidate how hypoxia profoundly reshapes the global surface-endocytome, and identify several hypoxia-induced antigens (CXADR, CD47, BSG, CD81, FXYD6), unique to or shared among GBM cultures. Importantly, we highlight the limited correlation between transcriptomics and proteomics, emphasizing the critical role of membrane protein enrichment strategies and targeted mass spectometry. Conclusions: These studies provide a comperehensive map of the surface-endocytome and its remodeling by hypoxia in GBM as a resource for target discovery. As proof-of-concept, we validate several proteins, either abundantly expressed in normoxia or induced by hypoxia, for further exploration as potential targets of immunotherapeutic approaches in GBM.
Project description:Background: Antibody and cell-based immunotherapies, e.g., antibody-drug-conjugates and CAR-T cells, targeted at cell-surface proteins, currently revolutionize clinical oncology. However, target selection warrants a better understanding of the surface-endocytome and how it is modulated by the tumor microenvironment. Here, we unravel the surface-endocytome landscape and its remodeling by hypoxia in primary cultures from glioblastoma (GBM) patients that currently lack targeted therapies. Methods. We employed a comprehensive approach for global and dynamic mapping of surfaceome and endocytosed (endocytome) proteins in primary GBM cultures at normoxia or hypoxia. Selected target candidates were validated by immunofluorescence analyses in patient tumor sections, spheroids, and 2D cultures, and were finally confronted by ADC cytotoxicity studies. Results: We reveal a heterogeneous surface-endocytome profile across GBM cultures from three patients representing different transcriptional subtypes. CD44 emerged as a commonly abundant surfaceome antigen across GBM cultures, and we established a direct correlation between CD44 endocytic activity and ADC cytotoxicity. We elucidate how hypoxia profoundly reshapes the global surface-endocytome, and identify several hypoxia-induced antigens (CXADR, CD47, BSG, CD81, FXYD6), unique to or shared among GBM cultures. Importantly, we highlight the limited correlation between transcriptomics and proteomics, emphasizing the critical role of membrane protein enrichment strategies and targeted mass spectrometry. Conclusions: These studies provide a comprehensive map of the surface-endocytome and its remodeling by hypoxia in GBM as a resource for target discovery. As a proof-of-concept, we validate several proteins, either abundantly expressed in normoxia or induced by hypoxia, for further exploration as potential targets of immunotherapeutic approaches in GBM.