Related Experiment Video
Updated: May 26, 2026
Membrane-SPINE: A Biochemical Tool to Identify Protein-protein Interactions of Membrane Proteins In Vivo
Published on: November 7, 2013
Dynamic disulfide scanning of the membrane-inserting Pf3 coat protein reveals multiple YidC substrate contacts
Christian Klenner1, Andreas Kuhn
1Institute of Microbiology and Molecular Biology, University of Hohenheim, 70599 Stuttgart, Germany.
Abstract:
The membrane insertase YidC inserts newly synthesized proteins into the plasma membrane. While defects in YidC homologs in animals and plants cause diseases, YidC in bacteria is essential for life. Membrane insertion and assembly of ATP synthase and respiratory complexes is catalyzed by YidC. To investigate how YidC interacts with membrane-inserting proteins, we generated single cysteine mutants in YidC and in the model substrate Pf3 coat protein. The single cysteine mutants were expressed and analyzed for disulfide formation during 30 s of synthesis. The results show that the substrate contacts different YidC residues in four of the six transmembrane regions. The residues are located either in the region of the inner leaflet, in the center, as well as in the periplasmic leaflet, consistent with the hypothesis that YidC presents a hydrophobic platform for inserting membrane proteins. In a YidC mutant where most of the contacting residues were mutated to serines, YidC function was severely disturbed and no longer active in a complementation test, suggesting that the residues are important for function. In addition, a Pf3 mutant with a defect in membrane insertion was deficient to contact the periplasmic residues of YidC.
Insights
The bacterial membrane insertase YidC is crucial for protein insertion. This study reveals YidC uses a hydrophobic platform to insert proteins, with specific residues essential for its function.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- The membrane insertase YidC is essential for bacterial viability and catalyzes the insertion of proteins like ATP synthase into the plasma membrane.
- Homologs of YidC in plants and animals are associated with diseases, highlighting its conserved importance in membrane protein biogenesis.
Purpose of the Study:
- To investigate the interaction mechanism between the membrane insertase YidC and its substrate proteins during membrane insertion.
- To identify specific YidC residues involved in the insertion process and their functional significance.
Main Methods:
- Generation and analysis of single cysteine mutants in YidC and the model substrate Pf3 coat protein.
- Disulfide bond formation assays to map residue contacts during protein synthesis (30s).
- Functional complementation tests of YidC mutants.
Main Results:
- The substrate protein contacts distinct YidC residues across its transmembrane regions, including inner, central, and periplasmic leaflets.
- Mutating key contacting residues in YidC to serines severely impaired its function.
- A Pf3 coat protein mutant with impaired membrane insertion showed reduced contact with periplasmic YidC residues.
Conclusions:
- YidC likely utilizes a hydrophobic platform to facilitate membrane protein insertion.
- Specific YidC residues identified are critical for its function in membrane protein biogenesis.
- The interaction interface between YidC and its substrate is important for efficient membrane insertion.
