Guo, Y.-W. | bioRxiv Science

bioRxiv2026

TRACER navigates rearrangement-driven sesterterpene chemical space via multimodal enzyme-product representation learning

Skeletal rearrangement drives the immense structural complexity of terpene, yet predicting it remains a formidable challenge due to sequence-function decoupling in terpene synthases. Here, we established TRACER (terpene rearrangement annotation via co-attentive enzyme-product representation), a multimodal framework mapping the latent associations between sequence-derived enzyme representations and product chemotypes. Retrospective validation proved TRACERs exceptional precision in predicting compound classes and discriminating skeletal rearrangement (SR) from non-skeletal rearrangement (NSR) pathways. TRACER-guided genome mining characterized two bifunctional synthases, FsPS and AcPS, uncovering four unprecedented carbon skeletons. Density functional theory calculations deciphered these cyclization cascades, pinpointing a critical 5/6/11 tricyclic intermediate as the key branching node for scaffold diversification. Mutagenesis and molecular dynamics simulations suggested that E305 in FsPS enables rearrangement by maintaining active-site water exclusion, whereas its alanine mutation causes premature carbocation quenching. Collectively, this work establishes a predictive paradigm for the rational discovery and mechanistic elucidation of complex terpene architectures.

synthetic biology↗

bioRxiv2022

Enhancing NeuroD1 Expression to Convert Lineage-Traced Astrocytes into Neurons

Regenerating functional new neurons in adult mammalian brains has been proven a difficult task for decades. Recent advancement in direct glia-to-neuron conversion in vivo opens a new field for neural regeneration and repair. However, this emerging new field is facing serious challenges from misuse of viral vectors to misinterpretation of conversion data. Here, we employ a variety of AAV vectors with different promoters and enhancers to demonstrate that astrocytes can be converted into neurons in a NeuroD1 dose-dependent manner in both wildtype (WT) and transgenic mice. Notably, astrocytes in WT mice were relatively easy to convert with higher conversion efficiency, whereas lineage-traced astrocytes in Aldh1l1-CreERT2 mice showed high resistance to reprogramming but were still converted into neurons after enhancing NeuroD1 expression with CMV enhancer. Furthermore, under two-photon microscope, we observed direct astrocyte-to-neuron conversion within 3 weeks of serial live imaging in the mouse cortex. We also demonstrated that high titre AAV reaching 1013 GC/ml caused severe neuronal leakage using a variety of AAV GFAP::GFP vectors, highlighting the necessity to inject low titre AAV into healthy brains to avoid artifactual results. Together, our studies suggest that lineage-traced astrocytes can be converted into neurons but require stronger conversion force such as enhanced NeuroD1 expression. Failure to recognize the difference between WT astrocytes and lineage-traced astrocytes in terms of conversion barrier will lead to misinterpretation of data.

neuroscience↗