Species name： Magnetotactic bacteria M0-1
Japan Advanced Institute of Science and Technology, Masaru Kawakami
While E. coli and Salmonella form a loose bundle of several, synchronously rotating flagella (20 nm in diameter) to produce thrust for swimming at about 30 ?m/sec, magnetobacteria MO-1 isolated from the Mediterranean Sea has two, much thicker flagellar apparatuses (100 nm in diameter), each made of seven flagellar filaments and 24 fibrils tightly packed in a bundle within a flexible sheath, for very fast swimming at 300 ?m/sec. But how the seven flagellar filaments can rotate so fast synchronously without much friction in the tight bundle was a big mystery. Structural analysis of the flagellar basal body of MO-1 by electron cryotomography revealed that each of the 24 fibrils has its own ring-like basal body and that the 24 fibril basal bodies and seven flagellar motors form a highly ordered, intertwined hexagonal array, just like the hexagonal array of the thick and thin filament of skeletal muscle. This intricate flagellar basal structure suggests that the fibrils counter-rotate between flagellar filaments to minimize the friction to allow the fast rotation of each flagellum. The animation and the mechanical model demonstrate how they rotate synchronously.
Architecture of a flagellar apparatus in the fast-swimming magnetotactic bacterium MO-1.
(2013.06.27)