Biology subjects

Daube, S. S.

Publications and source records attributed to Daube, S. S..

5 recordsLinked to original sources

bioRxiv2024

Autonomous biogenesis of the entire protein translation machinery excluding ribosomes

Recreating the conditions for autonomous biogenesis of the protein translation machinery is fundamental to our understanding of living systems and is essential for the assembly of minimal cell models. All components of the translation machinery, including the ribosomes, translation factors and aminoacyl tRNA synthetases, are made of proteins and are therefore involved in their own synthesis, posing a unique challenge for self-biogenesis. Here, we created physicochemical conditions for autonomous biogenesis of all the translation machinery, excluding the ribosome. We surface-immobilized synthetic genes coding for all thirty components as densely packed DNA brushes forming a reaction center that localizes, concentrates and catalyzes their simultaneous synthesis. To demonstrate their activity, we first determined empirically the minimal critical concentration of each translation protein required to initiate its own self-biogenesis in bulk solution. We then assembled a minimal gene expression reaction with all translation proteins at their critical concentrations. Under these dilute conditions, reporter proteins were not synthesized unless the DNA brushes encoded all the translation proteins, thereby demonstrating their co-synthesis, functionality and engagement in their own synthesis. This scenario of a complex biochemical process that amplifies itself can be generalized and extended to impact our understanding toward the design of autonomous self-replicating biological system.

synthetic biology↗

bioRxiv2024

Cell-free immuno-profiling on a genetically programmed biochip

Emerging cell-free synthetic biology approaches provide biosafe, cheap, and versatile genetic tools to advance therapeutic research and development. Combined with micro-fabrication technology, we developed a platform to quantitatively reconstitute interactions of cell-free synthesized antigens with antibodies and human receptors in miniaturized compartments on a silicon chip. Photolithographic surface patterning of protein traps and on chip expression from high density gene brushes generated a continuous surface density gradient of fluorescently labeled antigens. Antibodies binding to the antigen gradient generate a full binding curve in each single compartment for affinity determination. We used the SARS-CoV-2 antigens as a model to profile the specificity and affinity of monoclonal antibodies to > 30 viral epitopes synthesized simultaneously on one chip in a genotype-phenotype linked compartments. We further profiled polyclonal antibodies in minute volumes of human sera, revealing patient-specific epitope profiles that are difficult to detect by conventional approaches. Cell-free co-synthesis of the human ACE2 receptor with the viral Receptor-Binding-Domain yielded relative binding affinities to different SARS-CoV-2 variants. This rapid, quantitative, and on-chip genetically programmed approach allows to study complex protein-protein interactions independent of protein purification steps for human immuno-profiling with a fast response time for combating emerging pathogens.

bioengineering↗

bioRxiv2024

Transcription swells chromosomes in vitro

Transplanting chromosomes from living to artificial cells would impact our understanding of chromosome organization and DNA transactions, with implications for autonomous biological systems. Here, we transplanted Escherichia coli chromosomes into artificial cells, enabling real-time labeling, manipulation, and steady-state gene expression down to the single-molecule limit. Chromosomes stripped of native proteins transitioned from a swollen to compacted state induced by transcription inhibition, in contrast to protein-bound chromosomes retaining an organization with blobs. In a cell-free expression reaction, RNA polymerases were uniformly distributed along the entire chromosome and rapidly detached, consistent with a global transcriptional activity. We used tailored surfaces to capture and count 20 nascent proteins per hour from a single gene on the chromosome. We mapped stably bound condensins to the blobs, supporting a model where swelling by transcription is counterbalanced by condensin-mediated compaction. Our data suggest transplanted chromosomes as active gels organized by molecular machines.

biophysics↗

bioRxiv2023

A genetic circuit on a single DNA molecule as autonomous dissipative nanodevice

Realizing genetic circuits on single DNA molecules as self-encoded dissipative nanodevices is a major step toward miniaturization of autonomous biological systems. A circuit operating on a single DNA implies that genetically encoded proteins localize during coupled transcriptiontranslation to DNA, but a single-molecule measurement demonstrating this has remained a challenge. Here, we used a genetically encoded fluorescent reporter system with improved spatiotemporal resolution and observed the synthesis of individual proteins tethered to a DNA molecule by transient complexes of RNA polymerase, messenger RNA, and ribosome. Against expectations in dilute cell-free conditions where equilibrium considerations favor dispersion, these nascent proteins linger long enough to regulate cascaded reactions on the same DNA. We rationally designed a pulsatile genetic circuit by encoding an activator and repressor in feedback on the same DNA molecule. Driven by the local synthesis of only several proteins per hour and gene, the circuit dynamics exhibited enhanced variability between individual DNA molecules, and fluctuations with a broad power spectrum. Our results demonstrate that coexpressional localization, as a nonequilibrium process, facilitates single-DNA genetic circuits as dissipative nanodevices, with implications for nanobiotechnology applications and artificial cell design.

synthetic biology↗

bioRxiv2020

Decision-making in a synthetic cell: the limits of biological computation

We measured the dynamics of decision-making by a minimal bistable gene network integrated in a synthetic cell model, free of external perturbations. Reducing the number of gene copies from 105 to about 10 per cell revealed a transition from deterministic and slow computation to a fuzzy and rapid regime dominated by singleprotein fluctuations. Fuzzy computation appeared at DNA and protein concentrations 100-fold lower than necessary in equilibrium, suggesting rate enhancement by co-expressional localization. Whereas the high-copy regime was characterized by a sharp transition, hysteresis and robust memory, the low-copy limit showed incipient strong fluctuations, switching between states, and a signature of cellular individuality across the decision-making point. Our work establishes synthetic cells operating rapidly at the single molecule level to integrate gene regulatory networks with metabolic pathways for sustained survival with low energetic cost.One Sentence Summary Decision-making in a synthetic cell can be slow and precise or rapid and probabilistic by reducing the number of computing molecules by five decades down to single-molecule fluctuations.Competing Interest StatementThe Noireaux laboratory receives research funds from Arbor Biosciences, a distributor of the myTXTL cell-free protein synthesis kit.View Full Text

synthetic biology↗