Amphipathic helical ordering of the flagellar secretion signal of Salmonella flagellin.
Export of external flagellar proteins requires a signal located within their N-terminal disordered part, however, these regions do not share any significant sequence similarity suggesting that the secondary/tertiary structure might be important for recognition by the export gate. NMR experiments were performed to reveal the conformational properties of the flagellin signal sequence in vitro. It assumed a largely disordered fluctuating structure in aqueous environment, but acquired a folded structure containing an amphipathic helical portion in 50% MeOH or upon addition of SDS micelles which are known to promote hydrophobic interactions. Our observations raise the possibility that the signal sequence may partially undergo amphipathic helical ordering upon interaction with the recognition unit of the flagellar export machinery in a similar way as revealed for protein import into intracellular eukaryotic organelles mediated by targeting signals of high diversity.
Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok krt. 2, H-1117, Budapest, Hungary.
Orsolya
O
Tőke
Bio-Nanosystems Laboratory, Research Institute of Chemical and Process Engineering, University of Pannonia, Egyetem u. 10, H-8200, Veszprém, Hungary; Institute of Technical Physics and Materials Science, Centre for Energy Research, Konkoly-Thege u. 29-33, H-1121, Budapest, Hungary. Electronic address: von007@almos.vein.hu.
Ferenc
F
Vonderviszt
D000595:Amino Acid Sequence; D005407:Flagella / Q000737:chemistry*; D005408:Flagellin / Q000737:chemistry* / Q000235:genetics; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D000072756:Protein Conformation, alpha-Helical; D021382:Protein Sorting Signals / Q000235:genetics; D012475:Salmonella / Q000737:chemistry* / Q000235:genetics; D000069296:Type III Secretion Systems / Q000737:chemistry / Q000235:genetics
D021382:Protein Sorting Signals; D000069296:Type III Secretion Systems; D005408:Flagellin
Export signal; Flagellar export; Helical ordering; NMR; Type III secretion