점액세균 Myxococcus xanthus의 Slime Trail 생성에 관여하는 staA 유전자에 대한 연구
Study on the staA Gene Required for the Formation of Slime Trails in Myxococcus xanthus
점액세균 Myxococcus xanthus Slime Trail staA 유전자;
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A gene (staA), which is required for the production of slime trails in Myxococcus xanthus, has been identified. It encodes a 787 amino acid protein with eight tripeptide repeat motifs and a region showing homology to O-linked N-acetylglucosamine transferase. Null mutations in the staA gene caused defects in fruiting body development and reduction of spreading of cells on 1.5% agar surface. At first glance, it seemed that the staA mutant was defective in the adventurous(A) motility. Colonies of the mutant had flares with a smooth edge where no isolated, individual cells were visible. Single isolated mutant cells did not glide and no slime trails were observed for initial 4 h after the cells were placed on agar surface. Under the same condition, wild type cells glided normally and produced many long slime trails. It has been generally believed that the single isolated A-mutant cells do not glide. However videomicroscopy motion analysis indicated that the individual staA mutant cells retained an ability to glide on agar surface. Individual isolated mutant cells were observed to glide on the short slime trails which appeared six hours later after the cells were placed on agar surface. The gliding speed of the mutant on the slime trail was not reduced compared to the wile type cells. However the number and length of slime trails produced by the mutant were highly reduced. Therefore these results have suggested that the staA mutant is not defective in the motility machinery but in slime trail production.