Structure Identification: |
Cell Motil Cytoskeleton. 2008 Jul;65(7):553-62. | Dynamic rearrangement of F-actin organization triggered by host-specific plant signal is linked to morphogenesis of Aphanomyces cochlioides zoospores.[Pubmed: 18412254] | Cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone), a root releasing host-specific plant signal triggers chemotaxis and subsequent morphological changes in pathogenic Aphanomyces cochlioides zoospores before host penetration.
METHODS AND RESULTS:
The present study illustrates time-course changing patterns of cytoskeletal filamentous actin (F-actin) organization in the zoospores of A. cochlioides during rapid morphological changes (encystment and germination) after exposure to Cochliophilin A. Confocal laser scanning microscopic analysis revealed that F-actin microfilaments remained concentrated at ventral groove and diffusely distributed in peripheral cytoplasm of the zoospore. These microfilaments dramatically rearranged and changed into granular F-actin plaques interconnected with fine arrays during encystment. A large patch of actin arrays accumulated at one pole of the cystospores just before germination. Then the actin plaques moved to the emerging germ tube where a distinct cap of microfilaments was seen at the tip of the emerging hypha. Zoospores treated with an inhibitor of F-actin polymerization, latrunculin B or motility halting and regeneration inducing compound nicotinamide, displayed different patterns of F-actin in both zoospores and cystospores than those obtained by the induction of Cochliophilin A.
CONCLUSIONS:
Collectively, these results indicate that the host-specific plant signal Cochliophilin A triggers a dynamic polymerization/depolymerization of F-actin in pathogenic A. cochlioides zoospores during early events of plant-peronosporomycete interactions. | Arch Biochem Biophys. 2004 Dec 15;432(2):145-51. | A photoaffinity probe designed for host-specific signal flavonoid receptors in phytopathogenic Peronosporomycete zoospores of Aphanomyces cochlioides.[Pubmed: 15542053] | Aphanomyces cochlioides zoospores show chemotaxis to Cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone, 1), a host derived attractant, and also respond to 5,7-dihydroxyflavone (2) known as an equivalent chemoattractant.
METHODS AND RESULTS:
To investigate the chemotactic receptors in the zoospores, we designed photoaffinity probes 4'-azido-5,7-dihydroxyflavone (3) and 4'-azido-7-O-biotinyl-5-hydroxyflavone (4) considering chemical structure of 2. Both 3 and 4 had zoospore attractant activity which was competitive with that of 1. When zoospores were treated with the biotinylated photoaffinity probe followed by UV irradiation and streptavidin-gold or peroxidase-conjugated streptavidin, probe-labeled proteins were detected on the cell membrane. CONCLUSIONS: This result indicated that the 1-specific-binding proteins, a candidate for hypothetical Cochliophilin A receptor, were localized on the cell membrane of the zoospores.
This is the first experimental evidence of flavonoid-binding proteins being present in zoospores, using chemically synthesized azidoflavone as photoaffinity-labeling reagent. |
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