Project description:To survive during colonization or infection of the human body, microorganisms must defeat antimicrobial peptides, which represent a key component of innate host defense in phagocytes and on epithelia. However, is not known how the clinically important group of Gram-positive bacteria sense antimicrobial peptides to coordinate a directed defensive response. By determining the genome-wide gene regulatory response to human beta defensin 3 in the nosocomial pathogen Staphylococcus epidermidis, we discovered an antimicrobial peptide sensor system that controls major specific resistance mechanisms to antimicrobial peptides and is unrelated to the Gram-negative PhoP/PhoQ system. Wild type untreated in triplicate is compared to wild type treated in triplicate along with three mutants in triplicate with and without treatment of human beta defensin 3, totalling 30 samples
Project description:To survive during colonization or infection of the human body, microorganisms must defeat antimicrobial peptides, which represent a key component of innate host defense in phagocytes and on epithelia. However, is not known how the clinically important group of Gram-positive bacteria sense antimicrobial peptides to coordinate a directed defensive response. By determining the genome-wide gene regulatory response to human beta defensin 3 in the nosocomial pathogen Staphylococcus epidermidis, we discovered an antimicrobial peptide sensor system that controls major specific resistance mechanisms to antimicrobial peptides and is unrelated to the Gram-negative PhoP/PhoQ system. Keywords: Wild type control vs treated vs mutant
Project description:Staphylococcus aureus is a leading cause of hospital-associated infections. In addition, highly virulent strains of methicillin-resistant S. aureus (MRSA) are currently spreading outside health care settings. Survival in the human host is largely defined by the ability of S. aureus to resist mechanisms of innate host defense, of which antimicrobial peptides form a key part especially on epithelia and in neutrophil phagosomes. Here we demonstrate that the antimicrobial-peptide sensing system aps of the standard community-associated MRSA strain MW2 controls resistance to cationic antimicrobial peptides. The core of aps-controlled resistance mechanisms comprised the D-alanylation of teichoic acids (dlt operon), the incorporation of cationic lysyl-phosphatidylglycerol (L-PG) in the bacterial membrane (mprF), and the vraF/vraG putative antimicrobial peptide transporter. Further, the observed increased production of L-PG under the influence of cationic antimicrobial peptides was accompanied by the up-regulation of lysine biosynthesis. In noticeable difference to the aps system of S. epidermidis, only selected antimicrobial peptides strongly induced the aps response. Heterologous complementation with the S. epidermidis apsS gene indicated that this is likely caused by differences in the short extracellular loop of ApsS that interacts with the inducing antimicrobial peptide. Our study shows that the antimicrobial peptide sensor system aps is functional in the important human pathogen S. aureus, significant interspecies differences exist in the induction of the aps gene regulatory response, and aps inducibility is clearly distinguishable from effectiveness towards a given antimicrobial peptide. Keywords: Wild type control vs treated vs mutant Wild type untreated in triplicate is compared to wild type treated in triplicate along with three mutants in triplicate with and without treatment of indolicidin, totalling 30 samples
Project description:Staphylococcus aureus is a leading cause of hospital-associated infections. In addition, highly virulent strains of methicillin-resistant S. aureus (MRSA) are currently spreading outside health care settings. Survival in the human host is largely defined by the ability of S. aureus to resist mechanisms of innate host defense, of which antimicrobial peptides form a key part especially on epithelia and in neutrophil phagosomes. Here we demonstrate that the antimicrobial-peptide sensing system aps of the standard community-associated MRSA strain MW2 controls resistance to cationic antimicrobial peptides. The core of aps-controlled resistance mechanisms comprised the D-alanylation of teichoic acids (dlt operon), the incorporation of cationic lysyl-phosphatidylglycerol (L-PG) in the bacterial membrane (mprF), and the vraF/vraG putative antimicrobial peptide transporter. Further, the observed increased production of L-PG under the influence of cationic antimicrobial peptides was accompanied by the up-regulation of lysine biosynthesis. In noticeable difference to the aps system of S. epidermidis, only selected antimicrobial peptides strongly induced the aps response. Heterologous complementation with the S. epidermidis apsS gene indicated that this is likely caused by differences in the short extracellular loop of ApsS that interacts with the inducing antimicrobial peptide. Our study shows that the antimicrobial peptide sensor system aps is functional in the important human pathogen S. aureus, significant interspecies differences exist in the induction of the aps gene regulatory response, and aps inducibility is clearly distinguishable from effectiveness towards a given antimicrobial peptide. Keywords: Wild type control vs treated vs mutant
Project description:Streptococcus agalactiae (Group B Streptococcus, GBS) is a leading cause of early-onset neonatal bacterial infection. Evasion of innate immune defenses is critical to neonatal GBS disease pathogenesis. Effectors of the innate immune system such as antimicrobial peptides, as well as numerous antibiotics, target the peptidoglycan layer of the gram positive bacterial cell wall. The intramembrane-sensing histidine kinase class of two-component regulatory systems has recently been identified as important to the gram-positive response to cell wall stress. We identified and characterized the GBS homolog of LiaR, the response regulator component of the LiaFSR system and constructed site-directed, non-polar deletion mutations in the regulator gene liaR. GBS LiaR deletion mutant strains are more susceptible to cell wall active antibiotics (vancomycin and bacitracin) as well as antimicrobial peptides (colistin, nisin and the human cathelicidin LL-37) compared to isogenic wild-type GBS. LiaR mutant GBS are significantly attenuated in mouse models of both GBS sepsis and GBS pneumonia. To determine the genes regulated by LiaR that account for these defects, transcriptional profiling was performed using DNA microarray analysis, comparing wild-type GBS to LiaR mutant GBS under non-stressed conditions. Two separate RNA samples were extracted for each condition. One flip-dye replicate (2 hybridizations) was obtained for each pair of RNA samples for 4 hybridizations total.
Project description:We use the zebrafish embryo model to study the innate immune response against Staphylococcus epidermidis. Therefore, we injected S. epidermidis (and three controls groups) into the yolk at 2 hpf and samples at mutiple timepoints. Gene expression profiles were obtained at 6, 30, 54, 78, 102 and 126 hpi by microarrays. The results show that the gram-positive bacterium S. epidermidis induces a late immune response with a strong response at 102 hpi.
Project description:Lantibiotics are highly modified peptides that are part of the bacteriocin family of antimicrobial peptides. We have identified a Phr peptide quorum sensing system (TprA/PhrA) that controls the expression of a lantibiotic gene cluster in the Gram-positive human pathogen, Streptococcus pneumoniae. We have characterized the basic mechanism for a Phr peptide signaling system in S. pneumoniae D39 and found that it induces expression of the lantibiotic genes when pneumococcal cells are at high density in the presence of galactose, a main sugar of the human nasopharynx, a highly competitive microbial environment. In this study we used RNA-seq analysis to examine the changes in relative transcript amounts caused by ∆tprA and ∆phrA mutations or the addition of the 10-residue synthetic PhrA peptide. These analyses reveal that PhrA peptide addition induces the transcription of a cluster of lantibiotic gene that appear to process and provide immunity to a lantibiotic peptide. In addition, TprA, a transcriptional factor regulated by a Phr peptide, autoregulates its own transcription.
Project description:Streptococcus agalactiae (Group B Streptococcus, GBS) is a leading cause of early-onset neonatal bacterial infection. Evasion of innate immune defenses is critical to neonatal GBS disease pathogenesis. Effectors of the innate immune system such as antimicrobial peptides, as well as numerous antibiotics, target the peptidoglycan layer of the gram positive bacterial cell wall. The intramembrane-sensing histidine kinase class of two-component regulatory systems has recently been identified as important to the gram-positive response to cell wall stress. We identified and characterized the GBS homolog of LiaR, the response regulator component of the LiaFSR system and constructed site-directed, non-polar deletion mutations in the regulator gene liaR. GBS LiaR deletion mutant strains are more susceptible to cell wall active antibiotics (vancomycin and bacitracin) as well as antimicrobial peptides (colistin, nisin and the human cathelicidin LL-37) compared to isogenic wild-type GBS. LiaR mutant GBS are significantly attenuated in mouse models of both GBS sepsis and GBS pneumonia. To determine the genes regulated by LiaR that account for these defects, transcriptional profiling was performed using DNA microarray analysis, comparing wild-type GBS to LiaR mutant GBS under non-stressed conditions.
Project description:Alpha-mangostin (α-MG) is a natural xanthone reported to exhibit rapid bactericidal activity against Gram-positive bacteria, and may therefore have potential clinical application in healthcare sectors. This study sought to identify the antibacterial mode of action of α-MG against Staphylococcus epidermidis RP62A through RNA-sequencing technology.