Project description:Tigecycline, a protein translation inhibitor, is a treatment of last resort for infections caused by the opportunistic multidrug resistant human pathogen Acinetobacter baumannii. However, strains resistant to tigecycline were reported not long after its clinical introduction. Translation inhibitor antibiotics perturb ribosome function and induce the reduction of (p)ppGpp, an alarmone involved in the stringent response that negatively modulates ribosome production. Through RNA sequencing, this study revealed a significant reduction in the transcription of genes in citric acid cycle and cell respiration, suggesting tigecycline inhibits or slows down bacterial growth. Our results indicated that the drug-induced reduction of (p)ppGpp level promoted the production but diminished the degradation of ribosomes, which mitigates the translational inhibition effect by tigecycline. The reduction of (p)ppGpp also led to a decrease of transcription coupled nucleotide excision repair which likely increases the chances of development of tigecycline resistant mutants. Increased expression of genes linked to horizontal gene transfer were also observed. The most upregulated gene, rtcB, involving in RNA repair, is either a direct tigecycline stress response or is in response to the transcription de-repression of a toxin-antitoxin system. The most down-regulated genes encode two b-lactamases, which is a possible by-product of tigecycline-induced reduction in transcription of genes associated with peptidoglycan biogenesis. This transcriptomics study provides a global genetic view of why A. baumannii is able to rapidly develop tigecycline resistance.
2020-08-03 | GSE131451 | GEO
Project description:RNA-seq of tigecycline-resistant and tigecycline-susceptible K. pneumoniae strains
Project description:Comparisson of expression profiling of a etrA deletion mutant strain (experimental sample) with that of the wild type Shewanella oneidensis MR-1 strain to assess global direct/indirect genetic regulation EtrA in Shewanella oneidensis MR-1 shares 73.6% and 50.8% amino acid sequence identity with the oxygen-sensing regulator Fnr in E. coli and Anr in Pseudomonas aeruginosa, respectively; however, its regulatory role of anaerobic metabolism in Shewanella spp. is complex and not well understood. Whole-genome expression profiling using a etrA gene deletion mutant as the experimental sample and the wild type strain as the reference, determine that EtrA fine-tunes the expression of genes involved in various anaerobic metabolic pathways, including nitrate, fumarate and dimethyl sulfoxide reduction. Moreover, genes involved in prophage activation and and genes implicated in aerobic metabolism were also differentially expressed. In contrast to previous studies that attributed a minor regulatory role to EtrA in Shewanella spp., this study demonstrates that EtrA acts as a global transcriptional regulator and cofers physiological advantages to the strain under certain growth conditions.
Project description:Whole genome sequencing of SYBARIS Aspergillus spp. known to be multi-drug resistant and difficult to treat. Aim of this experiment is to investigate the genetic basis of susceptibility to disease and elucidate molecular mechanisms of drug resistance in these strains.
Project description:Tigecycline is a broad-spectrum active intravenous antibiotic that is also active against methicillin-resistant staphylococcus aureus. In Phase 3 and 4 clinical trials, increased all-cause mortality was observed in patients treated with tigecycline compared to patients in the control group. The reason for the increase is not yet clear. In this study, we found tigecycline could cause abnormal coagulation in tumor patients, especially in patients with hematological malignancies. The main manifestations were decreased fibrinogen and prolonged activated prothrombin time (APTT), thrombin time (TT) and D-dimer. In addition, functional studies have found that tigecycline could inhibit platelet adhesion and aggregation, and the patient's coagulation function could gradually recover after discontinuation. Gene sequencing results suggested that tigecycline could significantly regulate the expression of genes related to platelet function pathways, and could increase the incidence of single nucleotide polymorphisms and the number of alternative splices in CHO cells with tigecycline treatment. Abnormal platelet function and low numbers are common in patients with hematological malignancies. Our study could explain the mechanism of abnormal coagulation caused by tigecycline. At the same time, a warning should be given when doctors applied tigecycline to cure infections in tumor patients.