Mycoplasma mobileの運動蛋白質の配列解析による機能・構造予測

Structure and function prediction by sequence analysis for gliding proteins of Mycoplasma mobile

目次 正一*; 上野山 敦子*; 久保 純*; 宮田 真人*; 河野 秀俊; 由良 敬*; 郷 信広*

Metsugi, Shoichi*; Uenoyama, Atsuko*; Kubo, Jun*; Miyata, Makoto*; Kono, Hidetoshi; Yura, Kei*; Go, Nobuhiro*

Mycoplasma mobile glides at an average velocity of about 2.0 to 4.5 micro m/s, about ten times faster than the other mycoplasmas. The motile mechanism of M. mobile has been believed to differ from any previously identified mechanisms not only in bacteria but also in any other species. To reveal the mechanism, we carried out sequence analyses of Gli349 which is responsible for both adhesion to glass surfaces and motility, and its ortholog MYPU2110 from Mycoplasma pulmonis. We found that Gli349 contains 18 repeats of about 100 amino acid residues each in 3,183 residues, and MYPU2110 contains 22 in 3,216 residues. We also showed that the repeat was not homologous to any other known protein and therefore predicted three-dimensional structure. The model structure of Gli349 was proposed which fit well to the images obtained by electron microscopy, assuming that the cleavage by chymotrypsin tend to occur in the regions between the repeats, and that each repeat folds into an independent structural domain. Based on this model, with inhibitory antibodies and mutants, the regions directly involved in movements of M. mobile was suggested on Gli349 and Gli521, which is also involved in the gliding machinery. A further study suggested that Gli349 should be a "leg" for the motile apparatus with Gli521 that plays a role of a "crank" for M. mobile. In the presentation, such a unique motile mechanism of M. mobile being elucidated is introduced.