Project description:Plasmids are extrachromosomal genetic elements commonly found in bacteria. Plasmids are known to fuel bacterial evolution through horizontal gene transfer (HGT), but recent analyses indicate that they can also promote intragenomic adaptations. However, the role of plasmids as catalysts of bacterial evolution beyond HGT remains poorly explored. In this study, we investigate the impact of a widespread conjugative plasmid, pOXA-48, on the evolution of various multidrug-resistant clinical enterobacteria. Combining experimental and within-patient evolution analyses, we unveil that plasmid pOXA-48 promotes bacterial evolution through the transposition of plasmid-encoded IS1 elements. Specifically, IS1-mediated gene inactivations expedite the adaptation rate of clinical strains in vitro and foster within-patient adaptation in the gut. We decipher the mechanism underlying the plasmid-mediated surge in IS1 transposition, revealing a negative feedback loop regulated by the genomic copy number of IS1. Given the overrepresentation of IS elements in bacterial plasmids, our findings propose that plasmid-mediated IS transposition represents a crucial mechanism for swift bacterial adaptation.
Project description:The type VI secretion system (T6SS) is a highly sophisticated nanomachine widely used by bacteria to achieve competitive advantage and to potentiate horizontal gene transfer. Plasmid conjugation plays crucial roles in bacterial evolution by driving adaptation to environmental stimuli and pathogenicity. The lethal effect mediated by T6SS is detrimental to horizontal gene transfer by conjugation, while bacteria have evolved T6SS repression mechanisms regulated by plasmid to accomplish conjugative transfer. Two TetR family regulators encoded by large conjugative plasmid (LCP) in Acinetobacter baumannii have been proved similar in T6SS restriction, which seems redundant in function. Here, the global regulation roles and multiple DNA binding sites of two plasmid-sourced TetRs were identified. The two TetRs showed distinct preferences in similar roles of T6SS inhibition and binding with DNA probes. Crystal structures of TetRs were solved for illuminating the regulatory mechanism and possible reasons for difference in functions. In addition, plasmid-sourced TetRs also significantly downregulated biofilm formation and bacterial colonization, as well as influenced bacterial virulence in cultured cells and murine pneumonia infection models. Taken together, this work comprehensively elucidates the roles and regulatory mechanisms of TetRs and clarifies their similarity and difference in function, providing insights into plasmid encoded chromosome regulation pathways.
Project description:The type VI secretion system (T6SS) is a highly sophisticated nanomachine widely used by bacteria to achieve competitive advantage and to potentiate horizontal gene transfer. Plasmid conjugation plays crucial roles in bacterial evolution by driving adaptation to environmental stimuli and pathogenicity. The lethal effect mediated by T6SS is detrimental to horizontal gene transfer by conjugation, while bacteria have evolved T6SS repression mechanisms regulated by plasmid to accomplish conjugative transfer. Two TetR family regulators encoded by large conjugative plasmid (LCP) in Acinetobacter baumannii have been proved similar in T6SS restriction, which seems redundant in function. Here, the global regulation roles and multiple DNA binding sites of two plasmid-sourced TetRs were identified. The two TetRs showed distinct preferences in similar roles of T6SS inhibition and binding with DNA probes. Crystal structures of TetRs were solved for illuminating the regulatory mechanism and possible reasons for difference in functions. In addition, plasmid-sourced TetRs also significantly downregulated biofilm formation and bacterial colonization, as well as influenced bacterial virulence in cultured cells and murine pneumonia infection models. Taken together, this work comprehensively elucidates the roles and regulatory mechanisms of TetRs and clarifies their similarity and difference in function, providing insights into plasmid encoded chromosome regulation pathways.
2025-08-16 | GSE277925 | GEO
Project description:Experimental evolution with horizontal gene transfer in H. pylori
Project description:The rapid pace of evolution in bacteria is widely attributed to the promiscuous horizontal transfer and recombination of protein-coding genes. However, it is not known whether the same forces also drive the evolution of non-coding regulatory regions. Here we demonstrate that regulatory region can M-bM-^@M-^XswitchM-bM-^@M-^Y between non-homologous alternatives and that such switching is ubiquitous, occurring across the bacterial domain. We show that such regulatory switching strongly impacts promoter architecture and expression divergence. We further show that regulatory transfer facilitates rapid phenotypic diversification of a human pathogen. This regulatory mobility enables bacterial genes to access a vast pool of potential regulatory elements, facilitating efficient exploration of the regulatory landscape. Examination of 2 E. coli strains in 2 conditions