Unperturbing a Non-Helically Perturbed Bacterial Flagellar Filament: Salmonella typhimurium SJW23
| Autor: | Keren Nisani-Bizer, Shlomo Trachtenberg |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Salmonella typhimurium
Salmonella Molecular Sequence Data Biology Flagellum Flagellar filament medicine.disease_cause Protein Structure Secondary Spectral line Serine Protein filament symbols.namesake Crystallography Flagella Structural Biology symbols biology.protein medicine Amino Acid Sequence Molecular Biology Bessel function Flagellin Sequence Deletion |
| Zdroj: | Journal of Molecular Biology. 416:367-388 |
| ISSN: | 0022-2836 |
| DOI: | 10.1016/j.jmb.2012.01.003 |
| Popis: | Salmonella typhimurium SJW23 has a right-handed, non-helically perturbed filament of serotype gt with a unique surface pattern. Non-helical perturbations involve symmetry reduction along the five-start helical lines resulting in layer lines of fractional Bessel orders and a consequent seam. The flagellin gene, fliC 23 , which we sequenced, differs from the sequence of the canonic, plain SJW1655 flagellin, fliC 1655 . We modified discrete components of fliC 23 in order to localize, in the expressed filament, the submolecular site responsible for the non-helical perturbation. These modifications include (i) deleting the outermost domain D3 23 , (ii) replacing D3 23 with D3 1655 , (iii) substituting a hydrophilic α-helix at the interface between the neighboring domains D1 and D2 with a hydrophobic one from fliC 1655 , and (iv) substituting a serine/glycine pair in the loop connecting the modified α-helix to its neighbor; these modifications were made in the presence and absence of D3 23 . We used S. typhimurium SJW1655 both as a reference and as a source for ‘spare parts’. The symmetry of the constructs was assessed from the power spectra through changes in the layer lines at a height of 〈1/105〉 and 〈1/35〉 A − 1 , unique to the non-helical perturbation. Deleting D3 23 , either alone or in combination with various substitutions, or replacing it with D3 1655 transforms the non-helically perturbed filament into a plain one as judged by the disappearance of the typical layer lines from the power spectra. We conclude that the non-helical perturbation is a product of unique interactions in the D3 23 density shell. Whereas other minor structural changes may occur at the filaments interior, they are all helically symmetric. |
| Databáze: | OpenAIRE |
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