Movement of the F40 domain of flagellin during the morphological transition of bacterial flagella.
Flagella from Salmonella typhimurium were labeled with various amounts of fluorescein isothiocyanate. The site of labeling was identified as being predominantly in the exterior F40 domain. The fluorescence intensity decreased as the fluorescein density on the flagella increased, indicating self energy transfer between fluoresceins. The fluorescence of modified flagella was measured during the normal-to-curly morphological transition induced by alkaline pH. The morphological transition itself was simultaneously monitored by dark-field microscopy. Concomitant with the transition was a 25% increase in fluorescence for flagella heavily labeled with fluorescein. This was shown to be due to a decrease in the efficiency of energy transfer between fluoresceins on proximal flagellin subunits, implying that the F40 domains undergo relative movement apart during the morphological transition. Closer inspection of the domain movement and morphological transition as a function of pH reveals that the two processes are not exactly concomitant. This indicates the existence of intermediates during the transition. The fluorescence technique, outlined here, provides a means of directly monitoring an organizational 'switch' in the flagellin subunits during the actual morphological transition of flagella.
Seville
M
M
Molecular Dynamic Assembly Project, Exploratory Research for Advanced Technology Organization, Kyoto, Japan.
Ikeda
T
T
Hotani
H
H
D005407:Flagella / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D005408:Flagellin / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D016650:Fluorescein-5-isothiocyanate / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D009068:Movement; D012486:Salmonella typhimurium; D014357:Trypsin / Q000378:metabolism
D005408:Flagellin; D014357:Trypsin; D016650:Fluorescein-5-isothiocyanate