The Multiple flagellar Motor, evidence of evolution, or design ? elshamah.heavenforum.org/t1850-multiple-flagellar-motors#3091 iaincarstairs.wordpress/2013/03/25/as-smart-as-molecules/ One motor is fine, thanks, but how about seven, all hooked up in parallel? The MO-1 bacteria has a sheathed stack of seven flagella, interspersed with counter-rotating elements which reduce friction. This system was analysed by Osaka University in 2012 (see below). With this multiple motor, it swims at a rate of 300 micron/sec, slightly more than one metre/hour. A grain of talcum powder is about 10 micron in diameter. The seven filaments are enveloped with 24 fibrils in the sheath, and their basal bodies are arranged in an intertwined hexagonal array.. ..this strongly suggests that the fibrils counter- rotate between flagella in direct contact to minimize the friction of high-speed rotation of individual flagella in the tight bundle within the sheath to enable MO-1 cells to swim at about 300 μm/s. ..osaka-u.ac.jp/en/news/ResearchRelease/2012/11/20121127_1 These bacteria are about 225 nanometres wide, slightly less than a quarter of a micron – 44 side by side would be no wider than a grain of talcum powder – so if scaled up to the size of a small speedboat, perhaps 3 metres long, its proportional speed would be in excess of 14,000 kph – about ten times the speed of sound. Architecture of a flagellar apparatus in the fast-swimming magnetotactic bacterium MO-1 pnas.org/content/early/2012/11/21/1215274109.full.pdf Under the leadership of Juanfan Ruan, Researcher, KATO Takayuki, Assistant Professor, and NAMBA Keiichi, Professor, Graduate School of Frontier Biosciences, Osaka University, and Long-Fei Wu, Centre National de la Recherche Scientifique (CNRS), [French National Centre for Scientific Research], a group of researchers, using cryo-electron tomography, have clarified the way in which the flagellar apparatus in the fast-swimming magnetotactic bacterium MO-1 is constructed. Abstract The bacterial flagellum is a motility organelle that consists of a rotary motor and a helical propeller. The flagella usually work individually or by forming a loose bundle to produce thrust. However, the flagellar apparatus of marine bacterium MO-1 is a tight bundle of seven flagellar filaments enveloped in a sheath, and it has been a mystery as to how the flagella rotate smoothly in coordination. Here we have used electron cryotomography to visualize the 3D architecture of the sheathed flagella. The seven filaments are enveloped with 24 fibrils in the sheath, and their basal bodies are arranged in an intertwined hexagonal array similar to the thick and thin filaments of vertebrate skeletal muscles. This complex and exquisite architecture strongly suggests that the fibrils counter- rotate between flagella in direct contact to minimize the friction of high-speed rotation of individual flagella in the tight bundle within the sheath to enable MO-1 cells to swim at about 300 μm/s.
Posted on: Tue, 05 Aug 2014 23:36:27 +0000
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