Project description:We performed RNA-seq experiments to compare the gene expression profiles of cells expressing TEM-1 beta-lactamase with single-codon substitutions in the absence of beta-lactam antibiotics. Mutations with deleterious fitness effects in the absense of antibiotics also caused significant changes in gene expression, primarily in the induction of specific outer envelope stress response pathways and, in some cases, the mild-induction of a few genes in the heat-shock response pathway.
Project description:We performed RNA-seq experiments to compare the gene expression profiles of cells expressing single-codon substitutions in the antibiotic resistance genes NDM-1, CAT-I, or aadB in the absence of antibiotics. Mutations with deleterious fitness effects in the absense of antibiotics also caused significant changes in gene expression in a number of genes related to stress-response pathways including the regulator of colanic acid capsule synthesis (Rcs) response, the phage shock protein response (Psp), and the oxidative stress response. Fold differences in gene expression were mutation- and gene-dependent.
2022-12-31 | GSE199248 | GEO
Project description:Collateral fitness effects of mutations
Project description:Variation in gene expression arises from cis- and trans-regulatory mutations, which contribute differentially to expression divergence. Here, we compare the impacts on gene expression and fitness for cis- and trans-regulatory mutations affecting expression of the TDH3 gene in Saccharomyces cerevisiae. We use the effects of cis-regulatory mutations to isolate effects of trans-regulatory mutations caused by impacts on TDH3 from pleiotropic impacts on other genes, providing a rare distribution of pleiotropic effects. These pleiotropic effects were often, but not always, deleterious. For cis- and trans-regulatory mutations with similar effects on TDH3, trans-regulatory mutations had more widespread effects on gene expression, with distinct impacts on expression of genes downstream of TDH3. These differences between cis-and trans-regulatory mutations help explain their different contributions to regulatory evolution.
Project description:We found that several variants with 2-4 mutations on Higher Eukaryotes and Prokaryotes Nucleotide-binding (HEPN) domains showed undiminished on-target activity but markedly reduced collateral effects. Furthermore, transcriptome-wide off-target effects and cell growth arrest induced by wild-type Cas13d were found to be absent for a Cas13d variant. Thus, high-fidelity Cas13 variants with minimal collateral effects are now available for the targeted degradation of RNAs in basic research and therapeutic applications.
Project description:In adaptive evolution, an increase in fitness to an environment is frequently accompanied by changes in fitness to other environmental conditions, called cross-resistance and sensitivity. Although the networks between fitness changes affect the course of evolution substantially, the mechanisms underlying such fitness changes are yet to be fully elucidated. Herein, we performed high-throughput laboratory evolution of Escherichia coli under various stress conditions using an automated culture system, and quantified how the acquisition of resistance to one stressor alters the resistance to other stressors. We demonstrated that resistance changes could be quantitatively predicted based on changes in the transcriptome of the resistant strains. We also identified several genes and gene functions, for which mutations were commonly fixed in the strains resistant to the same stress, which could partially explain the observed cross-resistance and collateral sensitivity. The integration of transcriptome and genome data enabled us to clarify the bacterial stress resistance mechanisms.
Project description:The intrinsic collateral cleavage activity of Cas13d,which refers to the gRNA-independent degradation of bystander RNA, significantly limits its therapeutic potential. To extensively evaluate the collateral effects of hpCas13d genome-wide, we conducted RNA-seq analysis of the transcriptome in HEK293T cells after the transfections with dCas13d, wtCas13d, hpCas13d, and hfCas13d . Compared to dCas13d, wtCas13d with a PPIA gRNA (reported to induce the significant collateral cleavage) resulted in significant downregulations of thousands genes. In sharp contrast, hpCas13d and hfCas13d showed much less off-target genes, respectively. These findings demonstrate that hpCas13d exhibits reduced collateral activity, rendering it suitable for in vivo applications.