Related Experiment Video
Updated: Aug 8, 2026
10:50
Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale
Published on: March 14, 2019
Interactions between C ring proteins and export apparatus components: a possible mechanism for facilitating type III
Bertha González-Pedrajo1, Tohru Minamino, May Kihara
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA. bpedrajo@ifc.unam.mx
Molecular Microbiology
|May 9, 2006
Summary
Salmonella flagellar protein FliN is crucial for exporting other flagellar proteins. Mutations in FliN disrupt this export process and affect motor function.
Area of Science:
- Microbiology
- Molecular Biology
- Protein Biochemistry
Background:
- The flagellar switch proteins FliG, FliM, and FliN in Salmonella regulate motor function and flagellar assembly.
- FliN's role in the flagellar export system is not fully understood.
Purpose of the Study:
- To investigate the role of FliN in the flagellar export process.
- To identify the domains of FliN involved in export and protein interactions.
Main Methods:
- Construction and analysis of FliN deletion and truncation mutants.
- Complementation assays in Salmonella fliN null strains.
- Co-immunoprecipitation and protein complex purification (nickel-affinity chromatography).
Main Results:
- FliN C-terminal deletions abolish flagellar protein export and complementation ability.
- FliN interacts with FliH, a regulator of the FliI ATPase.
- A five-protein complex (FliG, FliM, FliN, FliH, FliI) was purified, suggesting a role in the export apparatus.
Conclusions:
- The C-terminus of FliN is essential for flagellar protein export.
- FliN acts as a scaffold, interacting with FliH to facilitate the assembly of the flagellar export apparatus.
- The C ring may serve as a docking site for export components.
Related Concept Videos
01:42Nuclear Export
The nucleus restricts several proteins within and allows others to pass. The restricted proteins possess a nuclear retention sequence or NRS, anchoring them to the nuclear lamins and preventing their transport to the cytosol. The non-restricted proteins, after their synthesis, are transported to their site of action, such as the cytosol or other organelles, with the help of nuclear export signals or NES.
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
01:34Nuclear Protein Sorting
Nuclear protein sorting is the selective trafficking of histones, polymerases, gene regulatory proteins into the nucleus and exporting RNAs and ribosomes to the cytosol. It is a tightly controlled process that regulates gene expression within a cell.
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
01:20Cotranslational Protein Translocation
Translocation of proteins across membranes is an ancient process that occurs even in bacteria and archaebacteria. In fact, the components of the translocation machinery are still conserved between prokaryotes and eukaryotes.
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
02:22Regulated mRNA Transport
In eukaryotes, transcription and translation are compartmentalized; an mRNA is first synthesized in the nucleus and then selectively transported to the cytoplasm for protein synthesis. Before transport, a pre-mRNA undergoes several steps of post-transcriptional modifications including splicing, 5' capping, and the addition of a poly-adenine tail. Various proteins bind to the pre-mRNA during these modifications. The mRNA transport takes place with the help of multiple proteins playing specific...
01:34Directing Proteins to the Rough Endoplasmic Reticulum
The organelle-specific signaling sequences direct proteins synthesized in the cytosol to their final destination like ER, mitochondria, peroxisomes, etc. Some of the proteins directed to ER are then trafficked via vesicles to other organelles within the cell or the extracellular environment through the Golgi complex. For example, the rough ER synthesizes soluble proteins for transportation to the lysosomes or secretion out of the cell. It can also synthesize transmembrane proteins that can...
01:42Directionality of Nuclear Transport
Ras-related nuclear protein or Ran is a small G protein that cycles between its GTP and GDP bound states. Ran specific regulators, a Ran GTPase Activating Protein or RanGAP present in the cytosol and a Ran guanine nucleotide exchange factor or RanGEF present inside the nucleus regulate GTP/GDP exchange. A high concentration of GTP inside the cells, in addition to this asymmetric distribution of Ran-specific regulators, leads to a higher RanGTP concentration inside the nucleus. This...