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Sequence analysis of the gliding protein Gli349 in Mycoplasma mobile

View Article: PubMed Central - PubMed

ABSTRACT

The motile mechanism of Mycoplasma mobile remains unknown but is believed to differ from any previously identified mechanism in bacteria. Gli349 of M. mobile is known to be responsible for both adhesion to glass surfaces and mobility. We therefore carried out sequence analyses of Gli349 and its homolog MYPU2110 from M. pulmonis to decipher their structures. We found that the motif “YxxxxxGF” appears 11 times in Gli349 and 16 times in MYPU2110. Further analysis of the sequences revealed that Gli349 contains 18 repeats of about 100 amino acid residues each, and MYPU2110 contains 22. No sequence homologous to any of the repeats was found in the NCBI RefSeq non-redundant sequence database, and no compatible fold structure was found among known protein structures, suggesting that the repeat found in Gli349 and MYPU2110 is novel and takes a new fold structure. Proteolysis of Gli349 using chymotrypsin revealed that cleavage positions were often located between the repeats, implying that regions connecting repeats are unstructured, flexible and exposed to the solvent. Assuming that each repeat folds into a structural domain, we constructed a model of Gli349 that fits well the shape and size of images obtained with electron microscopy.

No MeSH data available.


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Model of Gli349. Low resolution image of Gli349 obtained with electron microscopy (EM) is shown in gray shade. Repeat regions shown in ovals connected by lines are assigned into the EM image of Gli349. The N-terminus is placed at the far right side in (a), and at the far left side in (b). The length of each rod and angles between two rods are the average values over EM images (unpublished data).
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f6-1_33: Model of Gli349. Low resolution image of Gli349 obtained with electron microscopy (EM) is shown in gray shade. Repeat regions shown in ovals connected by lines are assigned into the EM image of Gli349. The N-terminus is placed at the far right side in (a), and at the far left side in (b). The length of each rod and angles between two rods are the average values over EM images (unpublished data).

Mentions: A preliminary EM image of Gli349 shows the shape of Gli349 to have an inverted Z-like structure and to be composed of at least four parts (Fig. 6). It also showed that the joint between rods 1 and 2 is very flexible, whereas the joint between rods 2 and 3 is very rigid (Fig. 6). We then tried to place the predicted structure of the repeat sequences on the image of Gli349, taking into account the rough estimation of the length of Gli349, and assuming that the lengths of the three rods are proportional to the number of residues and that the entire structure is a string-like filament. We found that there are two ways to place the repeats on the image: the N-terminus of Gli349 can be assigned to either the tip (model 1, Fig. 6a) or the base of the body of M. mobile (model 2, Fig. 6b). In both assignments, there are nine repeats and two non-repeat regions within the 43-nm rod 1 (Fig. 6). We can estimate that the length of one repeat is shorter than 4.8 nm (=43/9), which agrees well with the average size of the predicted repeat structures. Because Gli349 is predicted to have a transmembrane region near the N-terminus11 and with the mutation of Ser to Leu at 2770 (Uenoyama, A., Seto, S. and Miyata, M., unpublished data), where the mutation is to be located in the oval region in model 1, Gli349 cannot adhere to glass12, we propose that model 1 more accurately depicts the true structure of Gli349, though in both models the non-repeat regions correspond well to the flexible joints.


Sequence analysis of the gliding protein Gli349 in Mycoplasma mobile
Model of Gli349. Low resolution image of Gli349 obtained with electron microscopy (EM) is shown in gray shade. Repeat regions shown in ovals connected by lines are assigned into the EM image of Gli349. The N-terminus is placed at the far right side in (a), and at the far left side in (b). The length of each rod and angles between two rods are the average values over EM images (unpublished data).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5036628&req=5

f6-1_33: Model of Gli349. Low resolution image of Gli349 obtained with electron microscopy (EM) is shown in gray shade. Repeat regions shown in ovals connected by lines are assigned into the EM image of Gli349. The N-terminus is placed at the far right side in (a), and at the far left side in (b). The length of each rod and angles between two rods are the average values over EM images (unpublished data).
Mentions: A preliminary EM image of Gli349 shows the shape of Gli349 to have an inverted Z-like structure and to be composed of at least four parts (Fig. 6). It also showed that the joint between rods 1 and 2 is very flexible, whereas the joint between rods 2 and 3 is very rigid (Fig. 6). We then tried to place the predicted structure of the repeat sequences on the image of Gli349, taking into account the rough estimation of the length of Gli349, and assuming that the lengths of the three rods are proportional to the number of residues and that the entire structure is a string-like filament. We found that there are two ways to place the repeats on the image: the N-terminus of Gli349 can be assigned to either the tip (model 1, Fig. 6a) or the base of the body of M. mobile (model 2, Fig. 6b). In both assignments, there are nine repeats and two non-repeat regions within the 43-nm rod 1 (Fig. 6). We can estimate that the length of one repeat is shorter than 4.8 nm (=43/9), which agrees well with the average size of the predicted repeat structures. Because Gli349 is predicted to have a transmembrane region near the N-terminus11 and with the mutation of Ser to Leu at 2770 (Uenoyama, A., Seto, S. and Miyata, M., unpublished data), where the mutation is to be located in the oval region in model 1, Gli349 cannot adhere to glass12, we propose that model 1 more accurately depicts the true structure of Gli349, though in both models the non-repeat regions correspond well to the flexible joints.

View Article: PubMed Central - PubMed

ABSTRACT

The motile mechanism of Mycoplasma mobile remains unknown but is believed to differ from any previously identified mechanism in bacteria. Gli349 of M. mobile is known to be responsible for both adhesion to glass surfaces and mobility. We therefore carried out sequence analyses of Gli349 and its homolog MYPU2110 from M. pulmonis to decipher their structures. We found that the motif “YxxxxxGF” appears 11 times in Gli349 and 16 times in MYPU2110. Further analysis of the sequences revealed that Gli349 contains 18 repeats of about 100 amino acid residues each, and MYPU2110 contains 22. No sequence homologous to any of the repeats was found in the NCBI RefSeq non-redundant sequence database, and no compatible fold structure was found among known protein structures, suggesting that the repeat found in Gli349 and MYPU2110 is novel and takes a new fold structure. Proteolysis of Gli349 using chymotrypsin revealed that cleavage positions were often located between the repeats, implying that regions connecting repeats are unstructured, flexible and exposed to the solvent. Assuming that each repeat folds into a structural domain, we constructed a model of Gli349 that fits well the shape and size of images obtained with electron microscopy.

No MeSH data available.


Related in: MedlinePlus