Project description:In the era of synthetic biology, design, construction, and utilization of synthetic chromosomes with unique features provide a new strategy to study complex cellular processes such as aging. Herein, we successfully constructed the 884 Kb synXIII of Saccharomyces cerevisiae to investigate replicative aging using this synthetic strains. We verified that up-regulation of a rRNA-related transcriptional factor, RRN9, positively influenced replicative lifespan. Using SCRaMbLE system that enables inducible whole-genome rearrangement on synXIII, we obtained 20 SCRaMbLEd synXIII strains with extended lifespan. Transcriptome analysis revealed the expression of genes involved in global protein synthesis is up-regulated in longer-lived strains. We established causal links between genotypic change and the long-lived phenotype via reconstruction of some key structural variations observed in post-SCRaMbLE strains and further demonstrated combinatorial effects of multiple aging regulators on lifespan extension. Our findings underscored the potential of synthetic yeasts in unveiling the function of aging-related genes.
Project description:Synthetic biology has focused on engineering genetic modules that operate orthogonally from the host cells. A synthetic circuit, however, can be designed to reprogram the host proteome, which in turn enhances the function of the synthetic circuit. Here, we apply this holistic synthetic biology concept by exploiting the crosstalk between metabolic networks in cells, leading to a protein environment more favorable for protein synthesis. Specifically, we show that a local module expressing translation machinery can reprogram the bacterial proteome, changing the expression levels of more than 780 proteins. The integration of the proteins synthesized by the local modules and the reprogramed proteome generate a cell-free system that can synthesize a diverse set of proteins in different reaction formats, with up to 5-fold higher expression level than classical cell-free systems. Our work demonstrates a holistic approach that integrates synthetic and systems biology concepts. This approach has the potential to achieve outcomes not possible by only local, orthogonal circuits.
Project description:A chromosome size-dependent bias in meiotic recombination is in place to ensure that homologous chromosome pairing occurs for all chromosomes, including the smallest ones. This bias is clearly detectable during the assembly of the meiotic protein axis, the structure that compacts meiotic chromosomes and promotes recombination.To investigate the origin of the size bias, we mapped genome-wide occupancy of the meiotic axis protein Red1 in yeast strains containing chromosome fusions and synthetic chromosomes. Meiosis studies of the fusion and synthetic chromosomes further revealed that core centromeres influence the deposition of the axial element protein Red1 over distances >100kb, while pericentromeric regions co-evolved to reduce Red1 binding near centromeres and spread out Red1 along the chromosomes.
Project description:The Sc2.0 project is building a eukaryotic synthetic genome from scratch. A major milestone has been achieved with all individual Sc2.0 chromosomes assembled. Here, we describe consolidation of multiple synthetic chromosomes using advanced endoreduplication intercrossing with tRNA expression cassettes to generate a strain with 6.5 synthetic chromosomes. The 3D chromosome organization and transcript isoform profiles were evaluated using Hi-C and long-read direct RNA sequencing. We developed CRISPR Directed Biallelic URA3-assisted Genome Scan, or “CRISPR D-BUGS”, to map phenotypic variants caused by specific designer modifications, known as “bugs”. We first fine-mapped a bug in synthetic chromosome II (synII), and then discovered a combinatorial interaction associated with synIII and synX, revealing an unexpected genetic interaction that links transcriptional regulation, inositol metabolism and tRNASerCGA abundance. Finally, to expedite consolidation, we employed chromosome substitution to incorporate the largest chromosome (synIV), thereby consolidating >50% of the Sc2.0 genome in one strain.
Project description:In this project we aim to construct a tyrosine-producing E. coli strain through iterative steps of genome engineering. High PEP availability through knockout of the PTS was combined with the precise, in-place genomic integration of several engineering interventions, known to increase L-tyrosine production yields, to create a tyrosine-overproducing E. coli strain that can function as a platform for further engineering and optimization. Utilizing a design-build-test-learn (DBTL) cycle, an evolved pts-knockout E. coli strain was equipped with optimizations of the aroG, aroB and tyrA genes and cultivated under batch and fed-batch conditions. Subsequently, metabolomics, transcriptomics and proteomics samples from the fed-batch experiments were analyzed to inform the design of new genomic interventions.
Project description:Genetically Engineered Mouse Models (GEMMs) aid in understanding human pathologies and developing new therapeutics, yet recapitulating human diseases authentically in mice is challenging to design and execute. Advances in genomics have highlighted the importance of non-coding regulatory genome sequences controlling spatiotemporal gene expression patterns and splicing to human diseases. It is thus apparent that including regulatory genomic regions during the engineering of GEMMs is highly preferable for disease modeling, with the prerequisite of large-scale genome engineering ability. Existing genome engineering methods have limits on the size and efficiency of DNA delivery, hampering routine creation of highly informative GEMMs. Here, we describe mSwAP-In (mammalian Switching Antibiotic resistance markers Progressively for Integration), a method for efficient genome rewriting in mouse embryonic stem cells. We first demonstrated the use of mSwAP-In for iterative genome rewriting of up to 115 kb of the Trp53 locus, as well as for genomic humanization of up to 180 kb ACE2 locus in response to the COVID-19 pandemic. Second, we showed the hACE2 GEMM authentically recapitulated human ACE2 expression patterns and splicing, and importantly, presented milder symptoms without mortality when challenged with SARS-CoV-2 compared to the K18-ACE2 model, thus representing a more authentic model of infection. Lastly, we demonstrated serial genome writing by humanizing mouse Tmprss2 in a biallelic fashion, highlighting the versatility of mSwAP-In in mouse genome writing.
Project description:Genetically Engineered Mouse Models (GEMMs) aid in understanding human pathologies and developing new therapeutics, yet recapitulating human diseases authentically in mice is challenging to design and execute. Advances in genomics have highlighted the importance of non-coding regulatory genome sequences controlling spatiotemporal gene expression patterns and splicing to human diseases. It is thus apparent that including regulatory genomic regions during the engineering of GEMMs is highly preferable for disease modeling, with the prerequisite of large-scale genome engineering ability. Existing genome engineering methods have limits on the size and efficiency of DNA delivery, hampering routine creation of highly informative GEMMs. Here, we describe mSwAP-In (mammalian Switching Antibiotic resistance markers Progressively for Integration), a method for efficient genome rewriting in mouse embryonic stem cells. We first demonstrated the use of mSwAP-In for iterative genome rewriting of up to 115 kb of the Trp53 locus, as well as for genomic humanization of up to 180 kb ACE2 locus in response to the COVID-19 pandemic. Second, we showed the hACE2 GEMM authentically recapitulated human ACE2 expression patterns and splicing, and importantly, presented milder symptoms without mortality when challenged with SARS-CoV-2 compared to the K18-ACE2 model, thus representing a more authentic model of infection. Lastly, we demonstrated serial genome writing by humanizing mouse Tmprss2 in a biallelic fashion, highlighting the versatility of mSwAP-In in mouse genome writing.
Project description:<p><strong>BACKGROUND:</strong> Traditional Chinese medicine has used <em>Peucedanum praeruptorum</em> Dunn (Apiaceae) for a long time. Various coumarins, including the significant root constituents Praeruptorin (A-E), are the active constituents of the dried roots of P. praeruptorum. Previous transcriptomic and metabolomic studies attempted to elucidate the distribution and biosynthetic network of these medicinal-valuable compounds. However, the lack of a high-quality reference genome impedes an in-depth understanding of genetic traits and, thus, the development of better breeding strategies.</p><p><strong>RESULTS:</strong> The authors assembled a telomere-to-telomere genome by combining PacBio HiFi, ONT ultra- long and Hi-C data. The final genome assembly was approximately 1.798 Gb, assigned to 11 chromosomes and genome completeness >98%. Comparative genomic analysis suggested that <em>P. praeruptorum</em> experienced two WGD events like the ones in the Apiaceae family. By the transcriptomic and metabolomic analysis of the coumarin metabolic pathway, we presented coumarins' spatial and temporal distribution and the expression patterns of critical genes for its biosynthesis. Notably, the <em>COSY</em> and cytochrome <em>P450</em> genes showed tandem duplications on several chromosomes, which may be responsible for the high accumulation of coumarins.</p><p><strong>CONCLUSIONS:</strong> The authors obtained a T2T genome for <em>P. praeruptorum</em>, which provides molecular insights into the chromosomal distribution of the coumarin biosynthetic genes. This high-quality genome is an essential resource for designing engineering strategies for improving the production of these valuable compounds.</p>