Project description:To determine the optimal RNA-Seq approach for animal host-bacterial symbiont analysis, we compared transcriptome bias, depth and coverage achieved by two different mRNA capture and sequencing strategies applied to the marine demosponge Amphimedon queenslandica holobiont, for which genomes of the animal host and three most abundant bacterial symbionts are available.
Project description:Symbiosis is a ubiquitous phenomenon in nature, and these inter-species interactions have a massive impact on organisms, shaping the world around us today. The relationship between the partners in microbial symbioses have been described as existing along a parasitism-mutualism continuum, and the dynamics of this continuum are dependent upon numerous genotypic and environmental factors. Theoretical and experimental studies show that vertical transmission (VT) leads to the evolution of mutualistic traits, whereas horizontal transmission (HT) facilitates the emergence of parasitic features. However, these studies focused on phenotypic data, and we know little about underlying molecular changes at the genomic level. Here we show that a dramatic shift in the frequency of genetic variants, coupled with major changes in gene expression, allow an obligate intracellular bacterial symbiont to alter its position in the mutualism-parasitism continuum depending on the mode of between-host transmission. We found that increased virulence in horizontally transmitted chlamydiae residing in amoebae was a result of processes occurring at the infectious stage of the chlamydia’s developmental cycle. Specifically, genes involved in energy production required for extracellular survival as well as the type III secretion system (T3SS) - the symbiont’s primary virulence mechanism - were significantly upregulated. Our results identify the genomic and transcriptomic dynamics sufficient to favor parasitic or mutualistic strategies.
Project description:This SuperSeries is composed of the following subset Series: GSE11944: Mucosal Glycan Foraging Enhances the Fitness and Transmission of a Saccharolytic Human Distal Gut Symbiont GSE11953: Mucosal Glycan Foraging Enhances the Fitness and Transmission of a Saccharolytic Human Distal Gut Symbiont: ECF mutant GSE11962: Growth of B. thetaiotaomicron on purified host mucosal glycans and glycan fragments Refer to individual Series
Project description:Mycobacterium tuberculosis is a facultative intracellular pathogen, responsible for causing tuberculosis. The harsh environment in which M. tuberculosis survives requires this pathogen to maintain an evolutionary advantage. However, the apparent absence of horizontal gene transfer in M. tuberculosis imposes restrictions in the ways by which evolution can occur. Large scale changes in the genome can be introduced through genome reduction, recombination events and structural variation. Here, we identify a functional chimeric protein in the ppe38-71 locus, the absence of which is known to have an impact on protein secretion and virulence. To examine whether this approach was used more often by this pathogen we further develop software that detects potential gene fusion events from multigene deletions using whole-genome sequencing data. With this software we could identify a number of other putative gene-fusion events within the genomes of M. tuberculosis isolates. We were able to demonstrate the expression of one of these gene fusions at the protein level using mass spectrometry. Therefore, gene fusions may provide an additional means of evolution for M. tuberculosis in its natural environment whereby novel proteins and functions can arise.
Project description:The Sfh protein is encoded by self-transmissible plasmids involved in human typhoid and is closely related to the global regulator H-NS. We have found that Sfh provides a stealth function that allows the plasmids to be transmitted to new bacterial hosts with minimal effects on their fitness. Introducing the plasmid without the sfh gene imposes a mild H-NS- phenotype and a severe loss of fitness due to titration of the cellular pool of H-NS by the A+T-rich plasmid. This stealth strategy seems to be used widely to aid horizontal DNA transmission and has important implications for bacterial evolution.
Project description:Gene transfer agents (GTAs) are prophage-like entities found in many bacterial genomes that cannot propagate themselves and instead package ~5-15 kbp fragments of the host genome that can be subsequently transferred to related recipient cells. Although suggested to facilitate horizontal gene transfer in the wild, no clear physiological role for GTAs has been elucidated. Here, we demonstrate that the a-proteobacterium Caulobacter crescentus produces bona fide GTAs. The production of Caulobacter GTAs is tightly regulated by a novel transcription factor, RogA, that represses gafYZ, which are direct activators of GTA gene transcription. Cells lacking rogA or expressing gafYZ produce GTAs harboring an ~8.3 kbp fragment of the genome that can, after cell lysis, promote transfer of DNA into recipient cells. Notably, we find that GTAs promote the survival of Caulobacter in stationary phase and following DNA damage by providing recipient cells a template for homologous recombination-based repair. This function may be broadly conserved in other GTA-producing organisms and explain the prevalence of this unusual horizontal gene transfer mechanism.
Project description:Gene transfer agents (GTAs) are prophage-like entities found in many bacterial genomes that cannot propagate themselves and instead package ~5-15 kbp fragments of the host genome that can be subsequently transferred to related recipient cells. Although suggested to facilitate horizontal gene transfer in the wild, no clear physiological role for GTAs has been elucidated. Here, we demonstrate that the a-proteobacterium Caulobacter crescentus produces bona fide GTAs. The production of Caulobacter GTAs is tightly regulated by a novel transcription factor, RogA, that represses gafYZ, which are direct activators of GTA gene transcription. Cells lacking rogA or expressing gafYZ produce GTAs harboring an ~8.3 kbp fragment of the genome that can, after cell lysis, promote transfer of DNA into recipient cells. Notably, we find that GTAs promote the survival of Caulobacter in stationary phase and following DNA damage by providing recipient cells a template for homologous recombination-based repair. This function may be broadly conserved in other GTA-producing organisms and explain the prevalence of this unusual horizontal gene transfer mechanism.
Project description:Gene transfer agents (GTAs) are prophage-like entities found in many bacterial genomes that cannot propagate themselves and instead package ~5-15 kbp fragments of the host genome that can be subsequently transferred to related recipient cells. Although suggested to facilitate horizontal gene transfer in the wild, no clear physiological role for GTAs has been elucidated. Here, we demonstrate that the a-proteobacterium Caulobacter crescentus produces bona fide GTAs. The production of Caulobacter GTAs is tightly regulated by a novel transcription factor, RogA, that represses gafYZ, which are direct activators of GTA gene transcription. Cells lacking rogA or expressing gafYZ produce GTAs harboring an ~8.3 kbp fragment of the genome that can, after cell lysis, promote transfer of DNA into recipient cells. Notably, we find that GTAs promote the survival of Caulobacter in stationary phase and following DNA damage by providing recipient cells a template for homologous recombination-based repair. This function may be broadly conserved in other GTA-producing organisms and explain the prevalence of this unusual horizontal gene transfer mechanism.
Project description:Host-derived factors are sucked into midgut of mosquitoes during natural malaria transmission, but their influence on malaria transmission is largely unknown. We reported that mouse complement C3 taken into mosquitoes significantly promoted malaria transmission either in laboratory or in field. This effect was attributed to the reduction of microbiota abundance in mosquito midgut by host-derived C3 through direct lyses the predominant symbiont bacteria Elizabethkingia anopheles. Elizabethkingia anopheles symbiont bacteria were demonstrated to be detrimental to malaria sexual stages in mosquitoes. Strikingly, the promoted effect of host C3 on malaria transmission was confirmed by laboratory mosquitoes membrane-feeding on Plasmodium falciparum. Therefore, we reveal a novel strategy of malaria parasite to utilize host complement C3 to promote its transmission, and the administration of C3 inhibitor would provide us a novel strategy to control malaria transmission.
2024-08-01 | GSE271070 | GEO
Project description:Horizontal transmission of bacterial symbionts from Lagria villosa to plants