Title
Structural study of MPN387, an essential protein for gliding motility of a human pathogenic bacterium,Mycoplasma pneumoniae
Author
Yoshito Kawakita, Miki Kinoshita, Yukio Furukawa, Isil Tulum, Yuhei O Tahara, Eisaku Katayama, Keiichi Namba, Makoto Miyata
Year
2016
Journal
Journal of Bacteriology
Abstract
Mycoplasma pneumoniae is a human pathogen that glides on host cell surfaces with repeated catch and release of sialylated oligosaccharides. At a pole, this organism forms a protrusion called the attachment organelle, which is composed of surface structures, including P1 adhesin and the internal core structure. The core structure can be divided into three parts: terminal button, paired plates, and bowl complex, aligned in this order from the front end of the protrusion. To elucidate the gliding mechanism, we focused on a component protein of the bowl complex, MPN387, which is essential for gliding but dispensable for cytadherence. The predicted amino acid sequence showed the protein features a coiled-coil region spanning from residue 72 to 290 of the total 358 amino acids in the protein. Recombinant MPN387 proteins were isolated with and without an EYFP fusion tag and analyzed by gel filtration chromatography, circular dichroism spectroscopy, analytical ultracentrifugation, partial proteolysis, and rotary-shadowing electron microscopy. The results showed that MPN387 is a dumbbell-shaped homodimer of about 42.7 nm in length and 9.1 nm in diameter, that includes a 24.5 nm long central parallel coiled-coil part. The molecular image was superimposed onto the electron micrograph based on the localizing position mapped by fluorescent protein tagging. A proposed role of this protein in the gliding mechanism is discussed.
Instrument
J-720
Keywords
Circular dichroism, Secondary structure, Biochemistry