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Related Concept Videos

Adaptability of Cytoskeletal Filaments01:12

Adaptability of Cytoskeletal Filaments

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The cytoskeleton is a complex dynamic structure performing varied functions based on cellular requirements. The adaptability of the individual filaments in the cytoskeleton determines their ability to perform various functions within the cell. It can undergo rapid reorganization during processes like cell division or remain stable for several hours as in the interphase. The adaptability of these filaments depends on stringent regulatory mechanisms. The microfilament and microtubules of the...
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Disassembly of Intermediate Filaments01:35

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Intermediate filaments (IFs) do not undergo spontaneous disassembly. Enzymes, kinases, and phosphatases add and remove phosphates from specific sites to regulate their disassembly. The IF concentration in the cytoplasm also regulates the disassembly. If the concentration crosses a threshold, it activates the protein kinases in the vicinity, allowing the phosphorylation of IFs.
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Formation of Intermediate Filaments00:57

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Intermediate filaments are cytoskeletal proteins with higher tensile strength and flexibility than microfilaments and microtubules. Unlike the other two cytoskeletal proteins, intermediate filament formation lacks the enzymatic activity to hydrolyze nucleotides like ATP and GTP to generate energy for polymerization. Therefore, the formation of intermediate filaments is multistep self-assembly. The involvement of any accessory proteins in intermediate filament formation has not yet been...
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Cytoskeletal filaments are polymeric forms of smaller protein subunits. However, individual cytoskeletal filaments may easily disassemble or associate with other similar filaments to form rigid structures. Microfilaments, made of actin monomers, rely on actin-binding proteins to form bundles and create networks of individual actin filaments. Microtubules rely on microtubule-associated proteins (MAPs) to form sturdy cylindrical structures. However, the proteins involved in forming complex...
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Mechanism of Filopodia Formation01:39

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Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
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The intrinsic polarity of cells can be primarily attributed to two factors- i) the asymmetric accumulation of mobile components such are regulatory molecules and subcellular components across the cell and ii) the orientation of polar cytoskeletal filaments that make up the cytoskeletal networks, specifically microfilaments, and microtubules arranged along the axis of polarity. Interactions between the cytoskeletal filaments are crucial for the establishment and maintenance of the polar nature...
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Updated: Sep 30, 2025

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Structural basis of dynamic P5CS filaments.

Jiale Zhong1, Chen-Jun Guo1, Xian Zhou1

  • 1School of Life Science and Technology, ShanghaiTech University, Shanghai, China.

Elife
|March 14, 2022
PubMed
Summary
This summary is machine-generated.

Δ1-pyrroline-5-carboxylate synthase (P5CS) forms essential filaments for its enzymatic activity. Structural insights reveal how P5CS filamentation coordinates its domains, crucial for proline synthesis in health and agriculture.

Keywords:
Cryo-EMD. melanogasterDrosophilaP5CScytoophidiummetabolic enzymemolecular biophysicsproline synthesisstructural biology

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Area of Science:

  • Biochemistry
  • Structural Biology
  • Molecular Biology

Background:

  • Δ1-pyrroline-5-carboxylate synthase (P5CS) is a bifunctional enzyme critical for proline and ornithine synthesis.
  • Mutations in P5CS (ALDH18A1) cause human diseases and impair plant stress resistance.
  • P5CS is known to form cytoophidia in vivo and filaments in vitro, but its structural basis remains unclear.

Purpose of the Study:

  • To elucidate the structure of P5CS filaments.
  • To understand the relationship between P5CS structure, filamentation, and enzymatic function.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) was used to determine the structures of Drosophila P5CS.
  • Structures were solved for three distinct ligand-binding states.
  • Analysis of interfaces involved in filament assembly and stabilization.

Main Results:

  • The study determined the structures of Drosophila P5CS in three states at 3.1–4.3 Å resolution.
  • Distinct ligand-binding states and conformational changes in the GK and GPR domains were observed.
  • P5CS tetramers assemble into divergent helical filaments stabilized by multiple interfaces, and mutations disrupting these interfaces reduce activity.

Conclusions:

  • P5CS filamentation is essential for its catalytic function.
  • Filament assembly coordinates the GK and GPR domains, providing a structural basis for enzyme activity.
  • Understanding P5CS structure-function relationships has implications for human health and agriculture.