DAO 76:113-121 (2007)  -  doi:10.3354/dao076113

Base changes in the fliC gene of Edwardsiella tarda: possible effects on flagellation and motility

Jun Okuda1,*, Fumiyasu Murayama1, Eisuke Yamanoi1, Emi Iwamoto1, Satoru Matsuoka2, Mitsuaki Nishibuchi3, Toshihiro Nakai1

1Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8528, Japan
2Ehime Prefectural Chuyo Fisheries Experimental Station, Iyo, Ehime 799-3125, Japan
3Center for Southeast Asian Studies, Kyoto University, Kyoto 606-8501, Japan

ABSTRACT: Edwardsiella tarda is a broad host-range pathogen infecting both animals and humans. E. tarda isolates from red sea bream Pagrus major are non-motile, whereas isolates from Japanese eel Anguilla japonica and Japanese flounder Paralichthys olivaceus are motile with peritrichous flagella. We compared the fliC gene coding for flagellin (FliC) in motile and non-motile E. tarda strains isolated from diseased fish. Twenty-two amino acid residues differed in the predicted FliC amino acid sequences between non-motile and motile strains. There were no significant differences either in the upstream sequences regulating transcription of the fliC gene or in the fliC transcript levels between motile and non-motile strains. The predicted secondary structure of FliC in non-motile E. tarda differed from that of motile strains, and the modeled data suggested that the secondary structure may be the important factor responsible for non-flagellation in the non-motile strains.


KEY WORDS: Edwardsiella tarda · fliC gene sequence · Base changes · Flagellation · Motility · Red sea bream · Japanese flounder


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