Biology subjects

Zhou, T. H.

Publications and source records attributed to Zhou, T. H..

3 recordsLinked to original sources

bioRxiv2026

Unconventional biocatalytic strategies orchestrate synthesis of the nucleoside analog sinefungin

Sinefungin is a potent nucleoside antimetabolite of S-adenosylmethionine (SAM), yet its biosynthesis has remained unclear for decades. Here we detail the identification and characterization of the complete sinefungin biosynthetic gene cluster (BGC) from Streptomyces incarnatus NRRL 8089. In vitro and in vivo analyses demonstrate that the defining carbon-carbon (C-C) bond is formed not by the long-hypothesized PLP-dependent process, but by a vitamin B12-dependent radical SAM enzyme. Using isotope-labeled cofactors and substrates, we provide evidence that the adenosyl group of sinefungin atypically originates from adenosylcobalamin via a homolytic SH2 substitution, establishing a rare instance where adenosylcobalamin is enzymatically consumed during the reaction. Furthermore, the pathway utilizes a cryptic phosphorylation-dephosphorylation strategy to control intermediate processing and substrate recognition. We also characterize two peptide aminoacyl-tRNA ligases (PEARLs) that append alanines onto the nucleoside scaffold using tRNA-activated amino acids. The PEARLs act directly on small molecules rather than macromolecular substrates, with one PEARL capable of iterative elongation. Finally, we leverage these enzymes in a reduced multi-enzyme cascade to biosynthesize sinefungin. Together, these findings redefine radical-mediated C-C bond formation and pearlin enzyme versatility, unlocking biocatalytic possibilities to produce amino acid-nucleoside conjugates. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=131 SRC="FIGDIR/small/726688v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@10e48deorg.highwire.dtl.DTLVardef@d220ceorg.highwire.dtl.DTLVardef@167e60borg.highwire.dtl.DTLVardef@2fddec_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2026

Loss of LanC-like proteins impairs post-injury regeneration of aging muscles

The adult skeletal muscle regenerates robustly upon injury, but this regenerative capacity rapidly declines with age. In this study, we identify the lanthionine synthetase C-Like (LanCL) proteins, mammalian homologs of the bacterial peptide cyclase LanC, as positive regulators of muscle regeneration in middle-aged mice. In a barium chloride-induced injury model, we found the protein levels of LanCL1 and LanCL2 to increase during an early phase of regeneration in middle-aged (12-month-old) but not young adult (4-month-old) mice. Utilizing a mouse line lacking all three LanCL proteins (LanCL triple KO or LTKO), we examined a potential role of LanCL in injury-induced muscle regeneration. Consistent with an age-dependent function of LanCL, we observed a delayed regeneration of the tibialis anterior (TA) muscle after injury, as reflected by reduced sizes of regenerating myofibers in middle-aged (but not young) LTKO compared to age-matched WT mice. Although the pool size of quiescent satellite cells (Pax7+) was comparable between 12-month-old LTKO and WT muscles without injury, the number of Pax7+ cells was significantly higher in regenerating LTKO muscles at day 5 after injury, accompanied by drastically decreased numbers of MyoD+ and MyoG+ cells, as well as increased numbers of proliferating cells. In addition, we detected elevated expression of pro-inflammatory cytokines in regenerating LTKO muscles, while the number of macrophages was similar comparing LTKO and WT muscles. Taken together, our observations suggest that in aging muscles LanCLs are important for proper timing of inflammation resolution and regeneration upon injury.

physiology↗

bioRxiv2025

Pharmacological reduction of neutrophil infiltration reduces Clostridioides difficile infection severity

Clostridioides difficile is the leading cause of nosocomial infections and an urgent public health threat. This bacterial pathogen is challenging to treat due to antibiotic resistance and high recurrence rates, highlighting the need for additional therapeutic strategies. The host inflammatory response is a major driver of C. difficile-associated disease and associated with worse clinical outcomes. Currently, few strategies targeting the inflammatory response have been leveraged to treat CDI. Here, we show that administration of the prostaglandin E1 (PGE1) analog misoprostol markedly reduces CDI severity by modulating host immune responses. During CDI, misoprostol decreases circulating neutrophils and limits infiltration into the colon, reducing epithelial damage, intestinal pathology, and infection severity. Additionally, misoprostol reduces serum granulocyte colony-stimulating factor (G-CSF), an important cytokine in neutrophil mobilization, controlling neutrophil levels during CDI. Together, these findings highlight neutrophil infiltration as a key driver of C. difficile-associated disease and identify innate immune modulation as a potential host-directed therapeutic strategy.

immunology↗