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Author Topic:   Is it possible to identify the parts of a system objectively?
bluegenes
Member (Idle past 2477 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007


Message 12 of 12 (498545)
02-11-2009 5:56 PM
Reply to: Message 11 by Stagamancer
02-11-2009 3:53 PM


Stagamancer writes:
E.g. ID proponents often use the bacterial flagellum as an example of an IC system. However, molecular biologists, investigated this, and found the Type-III Secretory System (TTSS):
If you're interested in the famous flagellum, Stagamancer, you might enjoy these pages from Mark Pallen's blog. Pallen has made his own discovery of homology in the flagellum, but this is mainly about interesting work done by Keiichi Namba's Japanese team. You can see that new discoveries about the little machine are being made (several interesting things in 2008) and that Behe was very unwise to choose this as something he hoped could not evolve.
Amongst other things, on the second link I've listed, you can read this:
quote:
Last year Namba's group published the structure of FliI and confirmed the striking homology with the F-type ATPase enzymatic subunits. At that stage in the game, it had become clear that the ATPase was a universal component not just of flagellar export systems but also of non-flagellar type III secretion systems. Also, it was also clear that if one knocked out the gene for FliI, one abolished flagellar biosynthesis. Thus, just about everyone in the field accepted that FliI was an essential component of the flagellar apparatus and that it energised secretion of proteins through the protein export system. In other words, if there were anything to the idea, put forward by Behe and others in the ID movement, that the flagellum showed "irreducible complexity", even experts might have accepted that FliI was one of the "irreducible" components!!
BUT earlier this year, Minamino and Namba (and independently a team headed by Kelly Hughes in the US) overturned all our assumptions by showing that it was perfectly possible to make flagella without FliI--what you needed to do was knock out FliH at the same time. Somehow or other FliH, which usually interacts with FliI, gums up the export apparatus in the absence of FliI. So, bang goes another pillar of support for the ID argument! In fact, it appears that flagellar protein export is powered not primarily by the ATPase by the proton-motive force.
And there's more.
Pallen blog page one
Flagellum page two (very interesting)
part three (possible new homologies + Japanese video)
Pallen, incidentally, turned up once here on EvC and introduced himself, mentioning his "Rough Guide" book, but I didn't realise who he was at the time, so we missed an opportunity to discuss the flagellum with someone who has actually worked on the damned thing!
The blog stuff concerns new discoveries made over the last twelve months.

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 Message 11 by Stagamancer, posted 02-11-2009 3:53 PM Stagamancer has not replied

  
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