PMID:12949107
| Citation |
Fraser, GM, González-Pedrajo, B, Tame, JR and Macnab, RM (2003) Interactions of FliJ with the Salmonella type III flagellar export apparatus. J. Bacteriol. 185:5546-54 |
|---|---|
| Abstract |
FliJ, a 17-kDa protein, is a soluble component of the Salmonella type III flagellar protein export system that has antiaggregation properties and several other characteristics that suggest it may have a chaperone-like function. We have now examined this protein in detail. Ten-amino-acid scanning deletions covering the entire 147-amino-acid sequence were tested for complementation of a fliJ null strain; only the first and last deletions complemented. A few of the deletions, especially towards the C terminus, exerted a dominant negative effect on wild-type cells, indicating that they were actively interfering with function. Two truncated versions of FliJ, representing its N- and C-terminal halves, failed to complement and were not dominant. We tested for FliJ self-association by several techniques. Size-exclusion chromatography (Superdex 200) indicated an apparent molecular mass of around 50 kDa, which could reflect either multimerization or an elongated shape or both. Multiangle light scattering gave a peak value of 20 kDa, close to the molecular mass of the monomer. Analytical ultracentrifugation gave evidence for weak self-association as a trimer or tetramer. It was known from previous studies that FliJ interacts with the N-terminal region of FliH, a negative regulator of the ATPase FliI. Using both truncation and deletion versions of FliJ, we now show that it is its C-terminal region that is responsible for this interaction. We also show that FliJ interacts with the soluble cytoplasmic domain of the largest membrane component of the export apparatus, FlhA; although small deletions in FliJ did not interfere with the association, both truncated versions failed to associate, indicating that a substantial amount of the central region of the FliJ sequence participates in the association. We present a model summarizing these multiple interactions. |
| Links | |
| Keywords |
Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Biological Transport/physiology; Flagella/metabolism; Genetic Complementation Test; Membrane Proteins/genetics; Membrane Proteins/metabolism; Molecular Weight; Mutation; Protein Structure, Tertiary; Recombinant Proteins/genetics; Recombinant Proteins/metabolism; Salmonella/genetics; Salmonella/metabolism |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
References
See Help:References for how to manage references in EcoliWiki.
