Nope. Experts on TTSS assert that the chicken came before the egg. The TTSS system is a stripped down version of a flagella rather than the flagella being a new and improved hypodermic.
The TTSS are on "bugs" that live in higher animals and have lost functions rather than gained functions.
How do you "strip down" something that's irreducibly complex and wind up with anything useful?
[The poster nicknamed Mr. LLLICHY replied:] Nope. Experts on TTSS assert that the chicken came before the egg.
That might be slightly more convincing if the alleged "experts" were actually named, the fact that other experts disagree was acknowledged, and the evidence and reasoning allegedly supporting the "assertion" was stated.
After all, "experts assert" that the Moon landings were faked.
The TTSS system is a stripped down version of a flagella rather than the flagella being a new and improved hypodermic.
It "is", "is" it? I note that this is coming from the same poster who airily rejects similar lines of study which happen to produce conclusions he prefers not to accept, on the grounds that such reasoning is "inconclusive" or "incomplete".
And yet, as soon as there's a conclusion which supports his favored dogma, now that type of analysis is so completely conclusive that one need not speak of "seems that" or "is indicated", one can speak of what "is".
Fascinating.
Actually, since he won't cite the research, allow me:
Phylogenetic analyses of the constituents of Type III protein secretion systems.Oh, looky there: The authors only go so far as to say that they "suggest that the flagellar apparatus was the evolutionary precursor of Type III protein secretion systems."
Nguyen L, Paulsen IT, Tchieu J, Hueck CJ, Saier MH Jr.
Department of Biology, University of California at San Diego, La Jolla 92093-0116, USA.
Multicomponent Type III protein secretion systems transfer gram-negative bacterial virulence factors directly from the bacterial cytoplasm to the cytoplasm of a host eukaryotic cell in a process that may involve a single energy-coupled step. Extensive evidence supports the conclusion that the genetic apparatuses that encode these systems have been acquired independently by different gram-negative bacteria, presumably by lateral transfer. In this paper we conduct phylogenetic analyses of currently sequenced constituents of these systems and their homologues. The results reveal the relative relatedness of these systems and show that they evolved with little or no exchange of constituents between systems. This fact suggests that horizontal transmission of the genes encoding these systems always occurred as a unit without the formation of hybrid gene clusters. Moreover, homologous flagellar proteins show phylogenetic clustering that suggests that the flagellar systems and Type III protein secretory systems diverged from each other following very early duplication of a gene cluster sharing many (but not all) genes. Phylogenies of most or all of the flagellar proteins follow those of the source organisms with little or no lateral gene transfer suggesting that homologous flagellar proteins are true orthologues. We suggest that the flagellar apparatus was the evolutionary precursor of Type III protein secretion systems.J Mol Microbiol Biotechnol. 2000 Apr;2(2):125-44.
I leave it to the reader to note the large disparity between "we suggest" and "is".
I also leave it to the reader to wonder if that's why the poster didn't want to provide a link to the "support" for his claim of what "experts" have "asserted" what "is".
"It depends upon what the meaning of the word is means."The problem is that the "suggestion" of Nguyen et al has been cast into doubt by subsequent research. For example:
-- Bill Clinton, Testimony before the Grand Jury, August 17, 1998
Bacterial type III secretion systems are ancient and evolved by multiple horizontal-transfer events.Note the passage highlighted in red. For the color-blind -- or those wearing dogma-colored glasses -- I'll repeat it again: "The suggestion that TTSS genes have evolved from genes encoding flagellar proteins is effectively refuted."
Uri Gophna, Eliora Z. Ron, Dan Graur
Type III secretion systems (TTSS) are unique bacterial mechanisms that mediate elaborate interactions with their hosts. The fact that several of the TTSS proteins are closely related to flagellar export proteins has led to the suggestion that TTSS had evolved from flagella. Here we reconstruct the evolutionary history of four conserved type III secretion proteins and their phylogenetic relationships with flagellar paralogs. Our analysis indicates that the TTSS and the flagellar export mechanism share a common ancestor, but have evolved independently from one another. The suggestion that TTSS genes have evolved from genes encoding flagellar proteins is effectively refuted. A comparison of the species tree, as deduced from 16S rDNA sequences, to the protein phylogenetic trees has led to the identification of several major lateral transfer events involving clusters of TTSS genes. It is hypothesized that horizontal gene transfer has occurred much earlier and more frequently than previously inferred for TTSS genes and is, consequently, a major force shaping the evolution of species that harbor type III secretion systems.http://kimura.tau.ac.il/graur/ArticlesPDFs/gophnaetal2003.pdf
Also see: Evolution in (Brownian) space: a model for the origin of the bacterial flagellum.
[LLLICHY:] The TTSS are on "bugs" that live in higher animals and have lost functions rather than gained functions.
Another claim "conveniently" missing any citation or support, I note. And if the implication is that "bugs" (*smirk*) which have TTSS are only those which have "lost" the function of flagella for movement (thus "gaining" TTSS by "losing" part of the flagella), this begs the interesting question of why are there bacteria which have *BOTH* TTSS *and* flagella, like for example Salmonella and Yersinia...
Type Ill protein secretion systems (TTS systems), the subject of several recent reviews (Hueck, 1998; Galan and Collmer, 1999; Cheng and Schneewind, 2000; Staskawitz et al., 2000; Cornelius and Gijsegem, 2000; Plano et al., 2001) are found in many animal and plant pathogens and in at least one insect endosymbiont (Nguyen et al., 2000; Saltiel et al., 2001). With one exception, they are all proteobacteria, and that exception is Chlamydiaceae. Bacteria with TTS systems are usually host - cell associated at some time in their life histories, and the components of TTS systems are often virulence factors. In many of these systems, contact of the pathogen with host cells prompts delivery of bacterial proteins into the host-cell cytoplasm or cell membrane where they disrupt cellular functions to the benefit of the pathogen. Energy needed for delivery comes from ATP. Proteins of the secretion mechanism are conserved, but the secreted proteins tend to be unique to the bacterium secreting them. In proteobacteria, the TTS genes are clustered in the bacterial chromosome and have GC contents at variance with the rest of the genome, which suggests that they have been horizontally transferred. In the enterobacteria, the apparatus for secreting proteins by the TTS system is arranged in a supramolecular structure, the needle complex, which spans the inner and outer bacterial membranes, contains TTS proteins, and is thought to be the instrument of bacterial protein translocation into the host cell (Kubori et al., 1998. Blocker et al., 2001). Type Ill genes are homologous to those of the flagellar export apparatus from which they probably evolved.
Really? Could you please provide a cite for this, I never heard it before.