peter at carrot.mcb.uconn.edu
Thu Dec 15 12:32:08 EST 1994
In article <PWLEPP-151294102114 at schmidt2.mph.msu.edu>, PWLEPP at rrn.mph.msu.edu (Paul Lepp) says:
>A few months ago there was a discussion here about phylogenies based on
>heat shock proteins and a number of other proteins. From what I remember
>it seemed that the argument was made that eukaryotes could have arisen from
>the fusion of a gram pos. and an archea. Could someone be so kind as to
>pass along a few cites on the HSPs and the gram pos./archea connection.
These are the references concerning the actual analysis and data
of the HSP70 homologues:
R. S. Gupta, K. Aitken, M. Falah & B. Singh (1994) Cloning of
Giardia lamblia heat shock protein HSP70 homologs:
implications regarding origin of eukaryotic cells and of
endoplasmic reticulum [see comments] Proc Natl Acad Sci U S A
91: 2895-2899 (1994) 
Gupta, R.S., Golding, G.B. (1993) Evolution of HSP70 gene and its
implications regarding relationships between archaebacteria,
eubacteria and eukaryotes. J. Mol. Evol. 37:573-582
Gupta, R.S. and Singh, B. (1992) Cloning of the HSP70 gene from
Halobacterium marismortui: relatedness of archaebacterial
HSP70 to its eubacterial homologs and a model of the
evolution of the HSP70 gene. J. Bacteriol. 174, 4594-4605.
As the HSP70 homologues suggest relationships very distinct from
ATPases (and 16S rRNA) I had a closer look at the data. The
sequences show very convincingly a close association between
HSP70 homologues from gram positive bacteria and from
archaebacteria or Archaea (so far only sequences from two
Euryarcheota). The obtained tree are similar to the
glutaminsynthetase data (see citations below).
Concerning the close relationship between gram negative bacteria
and eukaryotes I think the authors and others completely mis- (or
over-)interpret the data. The trees they Gupta et al. calculated
are all unrooted. If one uses midpoint rooting (i.e., one
assumes a molecular clock) the root is placed between the
eukaryotes on one side and all the prokaryotes on the other side
(This was done by Sharon Shtang in here dissertation at the Univ.
of Toronto). The same result is obtained if one uses an
The front half of the HSP70 homologues is homologous to the MreB
proteins of E.coli and Bacillus (i.e. a gram positive and a gram
negative). We (Elena Hilario and I) did some so far unpublished
analyses including these proteins in a phylogenetic analyses of
the HSP70 homologues. Using parsimony, distance matrix or
maximum likelihood analysis, the MreB proteins always group
between Eukaryotes on one side and all the prokaryotes on the
other. As far as I can see there is no indication in the HSP70
data what so ever indicating a close association between gram
negative bacteria and eukaryotes. The insertion that according
to Gupta et al unites gram negative eubacteria and eukaryotes
appears in our analysis as an insertion that unites gram
positives and archaebacteria. A problem with the use of the mreB
proteins as an outgroup is that so far these mreB proteins have
only been found in eubacteria. Therefore, it might be that the
duplication that gave rise to HSP70 and mreB proteins occurred
only after the last common ancestor. However, the duplication
certainly preceded the separation of gram positives from purple
bacteria; therefore, the grouping of the archaebacterial HSP70s
with the gram positives is incompatible with the molecular
phylogenies that find a clear separation between archae- and
eubacteria. This position of the "root" is found, if we use a
computer generated alignment without further selection by hand,
but it is also obtained when we used only those regions of the
mreB proteins that were highly conserved and that could be
aligned without difficulties.
|-------- mreB E.coli
| |-------- mreB Bacilli
| |--------- eukaryotic HSP70 hom.
| |--- gram negative bacteria
| |-- gram positive bacteria
Citations concerning glutaminsynthetases:
Kumada, Y., Benson, D.R., Hillemann, D., Hosted, T.J., Rochford,
D.A., Thompson, C.J., Wohlleben, W., Tateno, Y. (1993)
Evolution of the glutamine synthase gene, one of the oldest
existing and functioning genes. Proc. Natl. Acad. Sci. USA
Tiboni, O., Cammarano, P., Sanangelantoni, A.M. (1993) Cloning
and sequencing of the gene encoding glutamine synthase I from
the archaeum Pyrococcus woesei: Anomalous phylogenies
inferred from analysis of archaeal and bacterial glutamine
synthase I sequences. J. Bacteriol. 175: 2961-2969
Brown, J.R., Masuchi, Y., Robb, F.T., Doolittle, W.F. (1994)
Evolutionary Relationships of Bacterial and Archaeal
Glutamine Synthetase Genes. J. Mol. Evol. 38, 566-576
Some other molecular markers that suggest (or rather are compatible
with) a close association between gram positives and
archaebacteria (with +/- good resolution):
Lazcano, Puente, Gogarten, unpublished.
Benachenhou-Lafha et al., 1993; Hilario and Gogarten, 1993.
F-ATPase subunit encoding DNA isolated from Methanosarcina
Sumi et al., 1992; Hilario and Gogarten, 1993.
Benachenhou-Lafha, N., Forterre, P. and Labedan, B. (1993)
Evolution of glutamate dehydrogenase genes: evidence for two
paralogous protein families and unusual branching patterns of
the archaebacteria in the universal tree of life. J. Mol.
Evol. 36, 335-346.
Hilario, E., Gogarten, J.P. (1993) Horizontal Transfer of ATPase
Genes -The Tree of Life becomes a Net of Life. BioSystems
Sumi, M., Sato, M.H., Denda, K., Date, T., Yoshida, M. (1992) A
DNA fragment homologous to F1-ATPase beta subunit was
amplified from genomic DNA of Methanosarcina barkeri.
Indication of an archaebacterial F-type ATPase. FEBS. Lett.
J. Peter Gogarten
University of Connecticut
Dept. Molecular and Cell Biology
75 North Eagleville Rd.
Storrs, CT 06269-3044
Phone: USA 203 486 4061
FAX: USA 203 486 1784
e mail: Gogarten at UConnVM.uconn.edu
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