Biology subjects

Guo, C.-J.

Publications and source records attributed to Guo, C.-J..

21 records · Page 2Linked to original sources

bioRxiv2021

Structural basis of dynamic P5CS filaments

The bifunctional enzyme {Delta}1-pyrroline-5-carboxylate synthase (P5CS) is central to the synthesis of proline and ornithine. Pathogenic mutations in P5CS gene (ALDH18A1) lead to neurocutaneous syndrome and skin relaxation connective tissue disease in humans, and P5CS deficiency seriously damages the ability to resist adversity in plants, which has an essential role in agriculture and human health. Recently, P5CS has been demonstrated forming the cytoophidium in vivo and filaments in vitro. However, the underlying mechanism for the function of P5CS filamentation and catalyze the synthesis of P5C is hardly accessible without structural basis. Here, we have succeeded in determining the full-length structures of Drosophila P5CS filament in three states at resolution from 3.1 to 4.3 [A] under cryo-electron microscopy, we observed the distinct ligand-binding states and conformational changes for GK and GPR domain separately. These structures show the distinctive spiral filament is assembled by P5CS tetramers and stabilized by multiple interfaces. Point mutations that deplete such interactions disturb P5CS filamentation and greatly reduce the activity. Our findings reveal a previously undescribed mechanism that filamentation is crucial for the coordination between GK and GPR domains, and provide insights into structural basis for catalysis function of P5CS filament.

biochemistry↗

bioRxiv2019

The proline synthesis enzyme P5CS forms cytoophidia in Drosophila

Compartmentation of enzymes via filamentation has arisen as a mechanism for the regulation of metabolism. In 2010, three groups independently reported that CTP synthase (CTPS) can assemble into a filamentous structure termed the cytoophidium. In searching for CTPS-interacting proteins, here we perform a yeast two-hybrid screening of Drosophila proteins and identify a putative CTPS-interacting protein, {Delta}1-pyrroline-5-carboxylate synthase (P5CS). Using Drosophila follicle cell as the in vivo model, we confirm that P5CS forms cytoophidia, which are associated with CTPS cytoophidia. Overexpression of P5CS increases the length of CTPS cytoophidia. Conversely, filamentation of CTPS affects the morphology of P5CS cytoophidia. Finally, in vitro analyses confirm the filament-forming property of P5CS. Our work links CTPS with P5CS, two enzymes involved in the rate-limiting steps in pyrimidine and proline biosynthesis, respectively.

cell biology↗

bioRxiv2018

Depletion of microbiome-derived molecules in the host using Clostridium genetics

The gut microbiota produce hundreds of molecules that are present at high concentrations in circulation and whose levels vary widely among humans. In most cases, molecule production has not been linked to specific bacterial strains or metabolic pathways, and unraveling the contribution of each molecule to host biology remains difficult. A general system to toggle molecules in this pool on/off in the host would enable interrogation of the mechanisms by which they modulate host biology and disease processes. Such a system has been elusive due to limitations in the genetic manipulability of Clostridium and its relatives, the source of many molecules in this pool. Here, we describe a method for reliably constructing clean deletions in a model commensal Clostridium, C. sporogenes (Cs), including multiply mutated strains. We demonstrate the utility of this method by using it to toggle off the production of ten Cs-derived molecules that accumulate in host tissues. By comparing mice colonized by wild-type Cs versus a mutant deficient in the production of branched short-chain fatty acids, we discover a previously unknown IgA-modulatory activity of these abundant microbiome-derived molecules. Our method opens the door to interrogating and sculpting a highly concentrated pool of chemicals from the microbiome.

microbiology↗