Biology subjects

Kuo, S.-T.

Publications and source records attributed to Kuo, S.-T..

4 recordsLinked to original sources

bioRxiv2026

GBactPro: cross-species bacterial promoter prediction using element-resolved promoter definitions

Accurate bacterial promoter prediction remains challenging across species, partly because conventional models often use fixed-length promoter windows that do not explicitly account for promoter architecture. Using promoter annotations derived from the Promoter Architecture Scanner (PAS), we found that training on sequences comprising the -35 element, spacer, and -10 element improved cross-species prediction compared with fixed-length promoter windows. Based on this element-resolved promoter definition, we developed GBactPro, a convolutional neural network-bidirectional long short-term memory (CNN-BiLSTM) model jointly trained on curated promoter data from 43 bacterial species. The jointly trained model achieved a mean AUROC of 0.9943 on held-out test sequences. Under matched-length benchmarking, GBactPro outperformed Promotech, iPro-MP, Prompt, and iPro-WAEL by 0.066-0.314 in mean AUROC. Genome-wide scanning of Escherichia coli achieved an AUROC of 0.979 and an AUPRC of 0.160 under stringent one-to-one promoter-site matching, increasing to 0.997 and 0.323, respectively, with a 100-bp positional tolerance. Unmatched predictions were enriched for H-NS binding, and independent H-NS-knockout data further supported the possibility that some predicted promoter-like regions are transcriptionally repressed. Together, these findings highlight the importance of promoter-sequence definition for cross-species prediction and demonstrate the potential of GBactPro for genome-wide promoter identification and biological interpretation.

genomics↗

bioRxiv2025

Core elements play distinct roles in promoter birth and transcriptional regulation

Gene expression shapes phenotypes and evolution. However, studies of gene regulation focus on transcription factors, overlooking core promoters. To investigate how promoters emerge and regulate transcription, we determined the sequence-function landscapes of core elements, -35 and -10, in constitutive and transcription factor-regulated promoters in Escherichia coli. Characterization of in vivo transcriptional landscapes and in vitro RNA polymerase-promoter interactions showed the -10 element as essential for promoter evolution from random sequences. In contrast, the -35 element, though broadly conserved, is dispensable for promoter birth. Instead, it exerts greater impact on gene regulation via coordinated interactions with transcription activators and RNA polymerase. We further showed that evolution fine-tunes the -35 and -10 sequences of transcription factor-regulated promoters to achieve near-maximal fold changes by lowering basal while elevating induced expression. A notable exception is PluxI, whose leaky expression provides a crucial baseline for initiating quorum sensing. These findings elucidate promoter design principles and underscore the interdependence and coevolution of core elements, RNA polymerase, and transcription factors.

systems biology↗

bioRxiv2025

Unveiling the Hidden: Dissecting Liraglutide Oligomerization Dual Pathways via Direct Mass Technology, Electron-Capture Dissociation, and Molecular Dynamics

Peptide therapeutics have revolutionized drug design strategies, yet the inherent structural flexibility and conjugated moieties of drug molecules present challenges in discovery, rational design, and manufacturing. Liraglutide, a GLP-1 receptor agonist conjugated with palmitic acid at its lysine residue, exemplifies these challenges by forming oligomers, which may compromise efficacy through progressive formation of aggregates. Here, we incorporate native mass spectrometry platforms including electron-capture dissociation (ECD), direct mass technology (DMT), and molecular dynamics (MD) to capture the early oligomerization process of liraglutide. Our findings reveal a restricted C-terminal region upon oligomer formation, as indicated by the reduced release of z-ions in ECD analysis. Additionally, we identified the formation of higher-order oligomers (n=25-62) by DMT, primarily stabilized by hydrophilic interactions involving preformed stable oligomers (n=14). Together, these integrative mass spectrometry results delineate a dual-pathway oligomerization process for liraglutide, demonstrating the power of mass spectrometry in uncovering hidden pathways of self-association. This approach underscores the potential of mass spectrometry as a key tool in the rational design and optimization of peptide-based therapeutics.

biophysics↗

bioRxiv2025

Unravel the start element and promoter architecture across the domain Bacteria

Core promoters comprise multiple elements whose interaction with RNA polymerase initiates transcription. Despite decades of research, substantial sequence and length variation of promoter elements has hindered efforts to elucidate their function and the evolutionary diversity of transcriptional regulation. Combining massively parallel assays, biophysical modeling, and functional validation, we systematically dissected the promoter architecture upstream of experimentally determined transcription start sites in 49 phylogenetically diverse bacterial genomes (GC content: 27.8-72.1%). We identified a conserved 3-bp promoter element, termed start, that dictates transcription start site selection and enhances transcription. We uncovered a four-region organization within the variable spacer element, whose sequence composition modulates transcription by up to 600-fold. We showed that the discriminator element is conserved in Terrabacteria but diverse in Gracilicutes, the two major bacterial clades. High discriminator sequence diversity in Gracilicutes likely reflects diversifying evolution, enabling promoter-encoded regulation to orchestrate global gene expression in response to growth rate changes. Together, our findings reveal broad conservation of bacterial promoter organization while highlighting regulatory divergence of promoter elements and RNA polymerase between Terrabacteria and Gracilicutes. Sequence and functional similarities between bacterial promoter elements and their archaeal and eukaryotic counterparts further suggest a shared evolutionary origin of promoter architecture.

microbiology↗