Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2022.09.08.507180

A membrane-associated light harvesting model is enabled by functionalized assemblies of gene-doubled TMV proteins

Dai, J.·Wilhelm, K. B.·Bischoff, A. J.·Pereira, J. H.·Dedeo, M. T.·Garcia-Almedina, D. M.·Adams, P. D.·Groves, J. T.·Francis, M. B.
View original source ↗Export metadata ↓

Abstract

Photosynthetic light harvesting requires efficient energy transfer within dynamic networks of light harvesting complexes embedded within phospholipid membranes. Artificial light harvesting models are valuable tools for understanding the structural features underpinning energy absorption and transfer within chromophore arrays. Most artificial light harvesting complexes are static or in the solution phase, rather than in a two-dimensional fluid environment as in natural photosynthesis. We have developed a method for attaching a protein-based light harvesting model to a supported lipid bilayer (SLB), which provides an extended fluid membrane surface stably associated with a solid substrate. The protein model consisted of the tobacco mosaic viral capsid proteins (TMV) that were gene-doubled to create a tandem dimer (dTMV). Assemblies of dTMV were shown to break the facial symmetry of the double disk to allow for differentiation between the disk faces. Single reactive lysine and cysteine residues were incorporated into opposing surfaces of each monomer of the dTMV assemblies. This allowed for the site-selective attachment of both chromophores for light absorption and a peptide for attachment to the SLB. A cysteine modification strategy using the enzyme tyrosinase was employed for the bioconjugation of a peptide containing a polyhistidine tag for association with SLBs. The dual-modified dTMV complexes showed significant association with SLBs and exhibited mobility on the bilayer. The techniques used herein offer a new method for protein-surface attachment and provide a platform for evaluating excited state energy transfer events in a dynamic, fully synthetic artificial light harvesting system. Significance StatementHere we have constructed a model photosynthetic membrane containing proteins, chromophores, lipids, and aqueous components, all of which can be modified in their composition. This model is based on an asymmetric disk assembly consisting of engineered tandem dimers of the tobacco mosaic viral capsid protein (dTMV). We have developed methods to achieve dye conjugation and attachment of a supported lipid bilayers (SLB) site selectively on distinct protein surfaces. These dye-labeled protein complexes exhibit mobility on the SLB, resulting in a dynamic model of light harvesting membranes using entirely synthetic components. Additionally, this unique asymmetric assembly of TMV and the facile methods for protein functionalization are expected to expand the tunability of model light harvesting systems.

Source connections

Explore related subjects

bioengineeringPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Dai, J., Wilhelm, K. B., Bischoff, A. J., Pereira, J. H., Dedeo, M. T., Garcia-Almedina, D. M., Adams, P. D., Groves, J. T., Francis, M. B.. 2022-09-10. A membrane-associated light harvesting model is enabled by functionalized assemblies of gene-doubled TMV proteins. https://doi.org/10.1101/2022.09.08.507180

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Synergy-informed bilevel optimization reveals joint-specific benefits for realistic exoskeleton torque prediction

Simulation-driven optimization can guide exoskeleton control design, but its utility is limited by the accuracy with which muscle coordination is predicted. Strict effort-minimization formulations predict non-physiological muscle shutdown under high exoskeleton assistance, leading to peak assistive torques that exceed values reported in human-in-the-loop experiments. We evaluated the accuracy of synergy-informed simulations at predicting assistance across four single-joint exoskeleton configurations: ankle plantarflexion, knee extension, hip flexion, and hip abduction. We implemented a bilevel optimization to predict a parameterized assistive torque that minimizes metabolic cost, with assisted muscle dynamics estimated via either effort-minimization simulations (minimizing muscle effort only) or synergy-informed simulations (minimizing muscle effort constrained to a synergy structure). We used experimental data from five unimpaired adults walking at their preferred speed and compared results descriptively between the two formulations within each subject. Assistance based on effort-minimization simulations shut down agonist muscle activations and overestimated peak assistive torque compared with experimental values. In contrast, constraining muscle controls to a synergy structure prevented non-physiological muscle shutdown and yielded assistive torques closer to those measured in human-in-the-loop experiments. This benefit was not observed equally across all assisted degrees of freedom or subjects, emerging only where no single synergy could be suppressed to unload the assisted muscles. Synergy weights can therefore be interpreted as joint-specific predictors of when simulations can reliably inform wearable robot design.

bioengineering↗
bioRxiv2026

Engineered microvessel networks -- Longitudinal transcriptomic profiling validates chip-grown tissues as a robust model for studying vasculature

Vascularised Organ-on-Chip (OoC) models are promising New Approach Methodologies (NAMs), but their translation requires validation for defined Contexts of Use (CoU). Here, we combine microfluidic microvessel networks (MVNs) with longitudinal bulk and single-cell RNA sequencing to determine how cell provenance influences engineered vascular phenotype. Stromal cell identity produced distinct network architectures and transcriptional trajectories, demonstrating that support cells, commonly treated as interchangeable, represent an important CoU variable. Primary human pancreatic microvascular endothelial cells failed to form stable perfusable networks, but supplementation with 10% Human Umbilical Vein Endothelial Cells (HUVECs) or Blood Outgrowth Endothelial Cells (BOECs) rescued self-assembly. Single-cell transcriptomics identified specialised endothelial populations associated with vascular morphogenesis, including tip, stalk, phalanx, endothelial to mesenchymal transition (EndMT) and pericyte-like endothelial cells. Failed networks lacked coherent endothelial specialisation, whereas rescued networks restored stabilising cell states and revealed FLRT2--UNC5B signalling within pericyte-like HUVECs, recapitulating a pathway implicated in angiogenic development in vivo. These findings establish cell provenance as a critical determinant of microvascular NAM performance and demonstrate how transcriptomic validation can define and strengthen the biological relevance of microvessel-on-chip models for specific CoUs.

bioengineering↗
bioRxiv2026

Benchmarking foundation models for resting-state functional magnetic resonance imaging time series in cognitive aging research

Foundation models trained on large neuroimaging datasets could help smaller studies investigate cognition from brain recordings. However, whether the foundation model-derived representations improve assessment of current cognition, prediction of follow-up cognition, or characterization of cognitive change remains unclear. We evaluated nine configurations from five model families that process regional resting-state functional magnetic resonance imaging time series, using 3,103 scans from 1,653 participants across two observational and five intervention aging cohorts. Primary frozen representations showed no consistent superiority over conventional functional connectivity for concurrent cognitive associations or diagnostic classification. Changing the readout improved selected concurrent cognitive associations without updating model weights, indicating that performance depended partly on how representations were extracted. Additional post-training and embedding alignment yielded gains in selected settings but did not consistently improve performance across outcomes. In the primary longitudinal analyses, imaging representations did not establish added value beyond baseline clinical measures. These findings show that readout choice influences concurrent cognitive associations, while the added value of these representations for longitudinal outcomes remains unestablished.

bioengineering↗