Biology subjects

Zeng, Y. C.

Publications and source records attributed to Zeng, Y. C..

5 recordsLinked to original sources

bioRxiv2024

Validation of DoriVac (DNA origami vaccine) efficacy in a metastatic melanoma model

Metastatic cancer, particularly metastatic melanoma, poses a significant therapeutic challenge due to its resistance to standard treatments and low five-year survival rate of 20-27%. Current therapies show limited success, highlighting the urgent need for novel interventions. Recent advances in cancer vaccine research show great promise in reducing disease recurrence, but these approaches still face challenges pertaining to antigen selection, ease of production, and programmability. To address some of these challenges, we have adapted the DoriVac platform to serve as a cancer vaccine against metastatic melanoma. DoriVac is a DNA origami-based vaccine platform that allows for the codelivery of antigens of choice and the CpG immune adjuvant at an optimal nanospacing to promote Th1 immune polarization. In our study, we observed a significant reduction in lung tumor nodules for mice treated with DoriVac in both the B16OVA and B16F10 melanoma mouse models. DoriVac also appears to be a safe and effective treatment, with no anti-drug antibodies, as indicated by lower anti-dsDNA levels. Importantly, we observed an amplified effect when DoriVac was combined with PD-L1 immune checkpoint blockade, leading to an even greater reduction in metastatic lung tumor nodules. Our results also indicate an increased activation of antigen presenting cells, NK cells, CD4+ T cells and CD8+ T cells. These findings suggest that DoriVac, particularly in combination with the PD-L1 immune checkpoint blockade, can serve as a promising immunotherapy against metastatic cancer.

synthetic biology↗

bioRxiv2024

The molecular structure of an axle-less F1-ATPase

F1Fo ATP synthase is a molecular rotary motor that can generate ATP using a transmembrane proton motive force. Isolated F1-ATPase catalytic cores can hydrolyse ATP, passing through a series of conformational states involving rotation of the central {gamma} rotor subunit and the opening and closing of the catalytic {beta} subunits. Cooperativity in F1-ATPase has long thought to be conferred through the {gamma} subunit, with three key interaction sites between the {gamma} and {beta} subunits being identified. Single molecule studies have demonstrated that the F1 complexes lacking the {gamma} axle still "rotate" and hydrolyse ATP, but with less efficiency. We solved the cryogenic electron microscopy structure of an axle-less Bacillus sp. PS3 F1-ATPase. The unexpected binding-dwell conformation of the structure in combination with the observed lack of interactions between the axle-less {gamma} and the open {beta} subunit suggests that the complete {gamma} subunit is important for coordinating efficient ATP binding of F1-ATPase.

biochemistry↗

bioRxiv2022

Optimizing CpG spatial distribution with DNA origami for Th1-polarized therapeutic vaccination

Multivalent presentation of ligands often enhances receptor activation and downstream signaling. DNA origami offers precise nanoscale spacing of ligands, a potentially useful feature for therapeutic nanoparticles. Here we introduce a "square block" DNA origami platform to explore the importance of spacing of CpG oligonucleotides, which engage Toll-like receptors and thereby act as danger signals for dendritic cells. Through in vitro cell-culture studies and in vivo tumor-treatment models, we demonstrate that square blocks induce Th1 immune polarization when CpG is spaced at 3.5 nm. We observe that this DNA origami vaccine enhances DC activation, antigen cross-presentation, CD8 T cell activation, Th1-polarized CD4 activation and NK cell activation. The vaccine also synergizes effectively with anti-PD-L1 for improved cancer immunotherapy in melanoma and lymphoma models and induces long-term T cell memory. Our results suggest that DNA origami may serve as an advanced vaccine platform for controlling adjuvant spacing and co-delivering antigens. One Sentence SummaryThis study developed a DNA origami-based cancer vaccine (DoriVac) that co-delivers antigen and CpG immune adjuvant with an optimal nanospacing for Th1 immune polarization.

synthetic biology↗

bioRxiv2020

Subunit epsilon of E. coli F1Fo ATP synthase attenuates enzyme activity by modulating central stalk flexibility

F1Fo ATP synthase functions as a biological rotary generator that makes a major contribution to cellular energy production. Proton flow through the Fo motor generates rotation of the central stalk, inducing conformational changes in the F1 motor that catalyzes ATP production via flexible coupling. Here we present a range of cryo-EM structures of E. coli ATP synthase in different rotational and inhibited states observed following a 45 second incubation with 10 mM MgATP. The structures generated describe multiple changes that occur following addition of MgATP, with the inhibitory C-terminal domain of subunit {varepsilon} ({varepsilon}CTD) disassociating from the central stalk to adopt a condensed "down" conformation. The transition to the {varepsilon}CTD down state increases the torsional flexibility of the central stalk allowing its foot to rotate by [~]50{degrees}, with further flexing in the peripheral stalk enabling the c-ring to rotate by two sub-steps in the Fo motor. Truncation mutants lacking the second helix of the {varepsilon}CTD suggest that central stalk rotational flexibility is important for F1Fo ATP synthase function. Overall this study identifies the potential role played by torsional flexing within the rotor and how this could be influenced by the {varepsilon} subunit.

biophysics↗

bioRxiv2020

Structural Analysis of a Filamentous Chaperonin from Sulfolobus solfataricus

Chaperonins are biomolecular complexes that assist protein folding. Thermophilic Factor 55 (TF55) is a group II chaperonin found in the archaeal genus Sulfolobus that has , {beta} and {gamma} subunits. Using cryo-electron microscopy, we have determined the structure of the {beta}-only complex of S. solfataricus TF55 complexes to 3.6-4.2 [A] resolution and a filamentous form to 5.2 [A] resolution. The structures of the TF55{beta} complexes formed in the presence of ADP or ATP highlighted an open state in which nucleotide exchange can occur before progressing in the refolding cycle. The structure of the filamentous state indicates how helical protrusions facilitate end-on-end interactions. SynopsisThe isolated complex and filamentous forms of TF55{beta} chaperonin from the thermophilic archaea Sulfolobus solfataricus are reported. Using cryo-EM, nucleotide-bound complexes of TF55{beta} at 3.6-4.2 [A] resolution reveal an open conformation, while a 5.2 [A] reconstruction of the filamentous chaperonin reveals contacts at the apical domain similar to crystal-packed structures.

biophysics↗