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Hsieh, K.-Y.

Publications and source records attributed to Hsieh, K.-Y..

3 recordsLinked to original sources

Identification of gene kinetics patterns improves RNA velocity and cell fate prediction using JuloVelo

Single-cell RNA velocity has transformed our capacity to predict future cell states from sequencing snapshots, but existing methods rely on constant or binary kinetic assumptions that fail to capture the heterogeneous splicing dynamics of cellular differentiation. Here we present JuloVelo, a deep learning framework that demonstrates that identifying gene kinetics patterns to initialize neural network training dramatically improves RNA velocity model performance. By pre-determining whether each gene follows a Circle, Complete induction, or Complete repression pattern across cellular differentiation, JuloVelo initializes training with pattern-matched, pre-trained network weights, effectively guiding the cell-specific kinetics optimization away from biologically implausible parameter regimes. Additionally, JuloVelo demonstrates that multiome datasets can also be processed and modeled by utilizing promoter chromatin accessibility to guide kinetics pre-determination, and integrates an in silico perturbation framework to simulate transcription factor modulation on cell fate. Validated across eight datasets spanning erythrogenesis, neurogenesis, and endocrinogenesis, JuloVelo consistently outperformed constant-rate and cell-specific models, resolving the entire five-lineage differentiation program in hippocampal neurogenesis. Multiome processing improved both intrinsic and extrinsic velocity stability, and JuloVelo reduced computational execution time by approximately 70% compared to cellDancer. JuloVelo is available as an open-source package at https://github.com/jhlabtw/JuloVelo.jl.

bioinformatics↗

Structural basis for the peptidoglycan editing activity of YfiH

Bacterial cells are encased in peptidoglycan (PG), a polymer of disaccharide N-acetyl-glucosamine (GlcNAc) and N-acetyl-muramic acid (MurNAc) cross-linked by peptide stems. PG is synthesized in the cytoplasm as UDP-MurNAc-peptide precursors, of which the amino-acid composition of the peptide is unique, with L-Ala added at the first position in most bacteria but L-Ser or Gly in some bacteria. YfiH is a PG-editing factor whose absence causes misincorporation of L-Ser instead of L-Ala into peptide stems; but its mechanistic function is unknown. Here we report the crystal structures of substrate-bound and product-bound YfiH, showing that YfiH is a cytoplasmic amidase that controls the incorporation of the correct amino acid to the nucleotide precursors by preferentially cleaving the nucleotide precursor byproduct UDP-MurNAc-L-Ser. This work reveals an editing mechanism in the cytoplasmic steps of peptidoglycan biosynthesis.

molecular biology↗

Molecular basis for the ATPase-powered substrate translocation by the Lon AAA+ protease

The Lon AAA+ (adenosine triphosphatases associated with diverse cellular activities) protease (LonA) converts ATP-fuelled conformational changes into sufficient mechanical force to drive translocation of the substrate into a hexameric proteolytic chamber. To understand the structural basis for the substrate translocation process, we have determined the cryo-electron microscopy (cryo-EM) structure of Meiothermus taiwanensis LonA (MtaLonA) at 3.6 [A] resolution in a substrate-engaged state. Substrate interactions are mediated by the dual pore-loops of the ATPase domains, organized in spiral staircase arrangement from four consecutive protomers in different ATP-binding and hydrolysis states; a closed AAA+ ring is nevertheless maintained by two disengaged ADP-bound protomers transiting between the lowest and highest position. The structure reveals a processive rotary translocation mechanism mediated by LonA-specific nucleotide-dependent allosteric coordination among the ATPase domains, which is induced by substrate binding.

biophysics↗