Deletion of an sRNA primes development in a multicellular bacterium
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ABSTRACT: Small non-coding RNAs (sRNAs) regulate gene expression of many biological processes. During growth, some myxobacteria produce an sRNA — Pxr — that blocks fruiting-body development, an aggregative multicellular process typically triggered by starvation. Deleting the pxr gene allows Myxococcus xanthus to develop despite nutrient availability, but Pxr binding targets and the genes regulated by Pxr remain unknown. Here, after showing that Pxr controls the temporal dynamics of development, we compare the transcriptomes of vegetative M. xanthus cells possessing vs lacking pxr. Over half of the genes impacted by pxr deletion are linked to development, including known and previously undiscovered critical regulators. Pxr also positively regulates genes associated with general metabolic processes. Our study discovers phenotypic effects of Pxr regulation with ecological importance, identifies the suite of genes this sRNA controls during vegetative growth and reveals a previously unknown developmental regulator. These findings provide insights into the molecular mechanism controlling myxobacterial development.
Project description:Myxococcus xanthus is a model organism for studying social behaviors and cell differentiation in bacteria. Upon nutrient depletion, M. xanthus cells initiate a developmental program that culminates in formation of spore-filled fruiting bodies and peripheral rods outside of fruiting bodies. Completion of this developmental program depends on fine-tuned spatial and temporal regulation of gene expression, intercellular communication, signaling by nucleotide-based second messengers, and motility. In order to understand stage-specific gene expression during growth and development, we extracted total RNA from vegetative cells (referred as 0 h of development) and from cells developed for 6, 12, 18 and 24 h under submerged conditions in two replicates.
Project description:Myxococcus xanthus is a model organism for studying social behaviors and cell differentiation in bacteria. Upon nutrient depletion, M. xanthus cells initiate a developmental program that culminates in formation of spore-filled fruiting bodies and peripheral rods outside of fruiting bodies. Completion of this developmental program depends on fine-tuned spatial and temporal regulation of gene expression, intercellular communication, signaling by nucleotide-based second messengers, and motility. In order to understand regulation of gene expression during growth and development, transcription start sites were identified using Cappable-seq. To this end, we extracted total RNA from vegetative cells (referred as 0 h of development) and from cells developed for 6, 12, 18 and 24 h under submerged conditions in two replicates.
Project description:In response to starvation, Myxococcus xanthus initiates a developmental program that results in the formation of spore-filled multicellular fruiting bodies. Here we have used cDNA microarray analysis to determine changes in the global gene expression at different time points of the developmental process. The expression of nearly 900 genes was found to be altered at least two-fold during development as compared to vegetative cells. Genes encoding proteins with typical vegetative functions such as protein synthesis and energy metabolism were transcriptionally down-regulated in the early stages of development. Among the 430 genes transcriptionally up-regulated during development genes with regulatory functions were overrepresented; underlining that fruiting body formation relies on a complex signalling network. Notably, almost 40% of all genes with increased expression at different stages of development encoded hypothetical proteins indicating a large unexplored potential of proteins important for fruiting body formation. Keywords: Time course of development with 9 time points 3 biological replicates each; normalized ratios to vegetative cells of DK1622 (wt) Cy5
Project description:Myxococcus xanthus is a gram negative rod-shaped delta proteobacterium that differentiates into environmentally resistant spores in response to starvation. Little is known about the sporulation mechanism in part because sporulation occurs in a subpopulation of cells undergoing a lenghtly complex multicellular developmental program. This developmental program requires a solid surface, motility, a minimum population density and a sophisticated network of inter and intra-cellular signals which direct some cells first to aggregate into multicellular fruiting bodies and then to sporulate exclusively within these fruiting bodies. However, it has previously been demonstrated that synchronous conversion of vegetative cells into myxospores can also be triggered in nutrient-rich liquid medium by addition of glycerol to 0.5 M. Here, we took advantage of the glycerol-induced sporulation process to gain information about the core M. xanthus sprorulation mechanism. We determined changes in the global gene expression at 0.5, 1, 2, and 4 hours after glycerol induction compared to vegetative cells (wild-type DK1622). The expression of nearly 1,500 genes was found to be significantly altered at least two-fold within four hours of glycerol-induced development. Most of the known core sporulation marker genes were up-regulated, whereas most genes required for proper aggregation and fruiting body formation were not significantly regulated. Keywords: Time course of glycerol-induced (0.5 M final conc.) development with 4 time points referenced to vegetative cells 3 biological replicates each; normalized ratios to vegetative cells of DK1622 (wt) Cy3
Project description:In Myxococcus xanthus 55% of the more than 250 two-component signal transduction systems (TCS) genes are orphan. We hypothesized that the histidine kinase SgmT and the response regulator DigR, which comprises a DNA binding domain of the HTH_Xer type, function together to regulate gene expression. We performed genome-wide expression profiling experiments to determine wether the same set of genes are differentially expressed in the ΔdigR and ΔsgmT mutants. 3 biological replicates each; normalized ratios to vegetative cells of DK1622 (wt) Cy5
Project description:In response to starvation, Myxococcus xanthus initiates a developmental program that results in the formation of spore-filled multicellular fruiting bodies. Here we have used cDNA microarray analysis to determine changes in the global gene expression at different time points of the developmental process. The expression of nearly 900 genes was found to be altered at least two-fold during development as compared to vegetative cells. Genes encoding proteins with typical vegetative functions such as protein synthesis and energy metabolism were transcriptionally down-regulated in the early stages of development. Among the 430 genes transcriptionally up-regulated during development genes with regulatory functions were overrepresented; underlining that fruiting body formation relies on a complex signalling network. Notably, almost 40% of all genes with increased expression at different stages of development encoded hypothetical proteins indicating a large unexplored potential of proteins important for fruiting body formation. Keywords: Time course of development with 9 time points
Project description:Myxococcus xanthus is a gram negative rod-shaped delta proteobacterium that differentiates into environmentally resistant spores in response to starvation. Little is known about the sporulation mechanism in part because sporulation occurs in a subpopulation of cells undergoing a lenghtly complex multicellular developmental program. This developmental program requires a solid surface, motility, a minimum population density and a sophisticated network of inter and intra-cellular signals which direct some cells first to aggregate into multicellular fruiting bodies and then to sporulate exclusively within these fruiting bodies. However, it has previously been demonstrated that synchronous conversion of vegetative cells into myxospores can also be triggered in nutrient-rich liquid medium by addition of glycerol to 0.5 M. Here, we took advantage of the glycerol-induced sporulation process to gain information about the core M. xanthus sprorulation mechanism. We determined changes in the global gene expression at 0.5, 1, 2, and 4 hours after glycerol induction compared to vegetative cells (wild-type DK1622). The expression of nearly 1,500 genes was found to be significantly altered at least two-fold within four hours of glycerol-induced development. Most of the known core sporulation marker genes were up-regulated, whereas most genes required for proper aggregation and fruiting body formation were not significantly regulated. Keywords: Time course of glycerol-induced (0.5 M final conc.) development with 4 time points referenced to vegetative cells
Project description:In response to starvation Myxococcus xanthus initiates a developmental program that culminates in the formation of fruiting bodies inside which the rod-shaped cells differentiate to spores. Fruiting body formation depends on intercellular communication and two intercellular signals are known, the A-signal and the C-signal. Five genes have been identified which are required for A-signal synthesis. To begin to understand the function of the genes required for A-signal synthesis, we have analysed gene expression in the asgA and the asgB mutant. Keywords: Vegetative cells of WT (DK1622) and AsgA mutant (DK5057) and AsgB mutant (DK4398) 3 biological replicates each; normalized ratios to vegetative cells of DK1622 (wt) Cy5
Project description:In response to starvation Myxococcus xanthus initiates a developmental program that culminates in the formation of fruiting bodies inside which the rod-shaped cells differentiate to spores. Fruiting body formation depends on intercellular communication and two intercellular signals are known, the A-signal and the C-signal. Five genes have been identified which are required for A-signal synthesis. To begin to understand the function of the genes required for A-signal synthesis, we have analysed gene expression in the asgA and the asgB mutant. Keywords: Vegetative cells of WT (DK1622) and AsgA mutant (DK5057) and AsgB mutant (DK4398)