Project description:Bacterial endospores, the transmissible forms of pathogenic bacilli and clostridia, are heterogeneous multilayered structures composed of proteins. These proteins protect the spores against variety of stresses, thus helping spore survival, and assist in germination, by interacting with the environment to form vegetative cells. Owing to the complexity, insolubility, and dynamic nature of spore proteins, it has been difficult to obtain their comprehensive protein profiles. The intact spores of Bacillus subtilis, Bacillus cereus, and Peptoclostridium difficile and their vegetative counterparts were disrupted by bead-beating in 6M urea under reductive conditions. The heterogeneous mixture was then double-digested with LysC and trypsin. Next, the peptide mixture was pre-fractionated with Zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) followed by reverse phase LC-FT-MS analysis of the fractions. ‘One-pot’ method is a simple, robust method that yields identification of >1000 proteins with high confidence, across all spore layers from Bacillus subtilis, Bacillus cereus, and Peptoclostridium difficile. This method can be employed for proteome-wide analysis of non-spore-forming as well as spore-forming pathogens. Analysis of spore protein profile will help to understand the sporulation and germination processes and to distinguish immunogenic protein markers.
Project description:By entering a reversible state of reduced metabolic activity, dormant microorganisms are able to contend with suboptimal conditions that would otherwise reduce their fitness. In addition, certain types of dormancy like sporulation, can serve as a refuge from parasitic infections. Phages are unable to attach to spores, but their genomes can be entrapped in the resting structures and are able to resume infection upon host germination. Thus, dormancy has the potential to affect both the reproductive and survival components of phage fitness. Here, we characterized the distribution and diversity of sigma factors in nearly 3,500 phage genomes. Homologs of bacterial sigma factors that are responsible for directing transcription during sporulation were preferentially recovered in phages that infect spore-forming hosts. While non-essential for lytic infection, when expressed in Bacillus subtilis, we demonstrate that phage-encoded sigma factors activated sporulation gene networks and reduced spore yield. Our findings suggest that the acquisition of host-like transcriptional regulators may allow phages to manipulate the expression of complex traits, like the transitions involved in bacterial dormancy.
Project description:Widespread in bacteria and archaea, Toxin-antitoxin (TA) systems have been recently demonstrated to function in phage defense. Here we characterize the anti-phage function of a type IV TA system, ShosTA. Using structural and biochemical approaches, we show that ShosT couples phosphoribosyltransferase and pyrophosphatase activities to disrupt purine metabolism, resulting in DNA duplication, cell filamentation and ultimate cell death. ShosA binds DNA and likely recruits other proteins to facilitate DNA recombination to antagonize ShosT’s toxicity
Project description:Two selected compounds, 2,4-disubstituted pyridine derivatives (11 and 15), revealed significant bactericidal activity against Mycobacterium tuberculosis deposited within human macrophages as well as against biofilm-forming tubercle bacilli. The mass spectrometry-based proteomics (LC-MS/MS) of the wild-type tubercle bacilli growing in the subinhibitory concentration of 11 or 15 revealed 15 overproduced proteins not detectable in the control cells including virulence-related proteins.
2022-11-02 | PXD035807 | Pride
Project description:Spore-forming bacteria in skim milk powders
Project description:An important lesson from the war on pathogenic bacteria has been the need to understand the physiological responses and evolution of natural microbial communities. Bacterial populations in the environment are generally forming biofilms subject to some level of phage predation. These multicellular communities are notoriously resistant to antimicrobials and, consequently, very difficult to eradicate. This has sparked the search for new therapeutic alternatives, including phage therapy. This study demonstrates that S. aureus biofilms formed in the presence of a non-lethal dose of phage phiIPLA-RODI exhibit a unique physiological state that could potentially benefit both the host and the predator. Thus, biofilms formed under phage pressure are thicker and have a greater DNA content. Also, the virus-infected biofilm displayed major transcriptional differences compared to an untreated control. Significantly, RNA-seq data revealed activation of the stringent response, which could slow down the advance of the bacteriophage within the biofilm. The end result would be an equilibrium that would help bacterial cells to withstand environmental challenges, while maintaining a reservoir of sensitive bacterial cells available to the phage upon reactivation of the dormant carrier population.