Thursday, May 15, 2008

Speaking of teeny-weeny Evinrudes...

In my last post I noted that PBS reran the Nova broadcast of Judgement Day: Intelligent Design on Trial. In it, we heard Judge Jones say "We've seen that," referring to a picture of a bacterial flagellum, similar to one already shown. The flagellum had been introduced as literally an outboard motor. This was not noted as a simile; it was not noted as a metaphor. However, I must say, that many times when I hear someone refer to something as literally something else, they frequently mean "No, not literally--when I say literally I really don't mean that literally."

Anyhow, Michael Behe's contention was that this structure, the bacterial flagellum, is irreducibly complex--that is, take away any single part and the thing doesn't function. That contention was seen to be flawed; part of the structure has quite successfully functioned as a delivery system for plague.

An article in Science for 15 February 2008 by Shou Furuike &al. (subscription required) describes an itty-bitty motor that also lacks a rather important part, yet apparently still functions. In this case it's not an Evinrude, it's a Yamaha, er, the Fo motor of the ATP synthase. And the part it's missing is the axle. The axle-less mutants do indeed rotate. The authors end the article with
Why is there superfluous robustness in the rotary mechanism of F1? Perhaps this began as a clumsy device, and then proceeded to sophistication. If so, ring-shaped AAA+ ATPases may all, in principle, be capable of producing torque, as suggested for helicases.

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