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closeThe supergroups and domain-associations in innate immunity
Posted by staalmannen on 30 Aug 2007 at 08:33 GMT
I got very interested in this article, based on a recent review (Staal&Dixelius, 2007 Trends in Plant Science) I made about the evolution of domain-associations of domains involved in innate immunity in both plants and animals (and related processes for sexual compatibility in fungi).
In this analysis (where the samples from other eukaryotic super groups are unfortunately lacking) some indications of the evolutionary history of the TIR and NOD domains in the two lineages (plants, animals) could be found:
Animal NOD proteins:
(TIR)-NOD-WD40 (prokaryote, endosymbiont)--> CARD-NOD-WD40 (Apaf1 and multiple genes in "lower" animals - only cell death regulation?) --> CARD-NOD-LRR (Nod1, Nod2 etc - specialization for immunity?) --> PYD-NOD-LRR (NALPs) and BIR-NOD-LRR
In addition there are C- and N-terminal truncations that have occured at multiple occasions, which are not included in this linear phylogeny.
Plant R genes
TIR-NOD-TPR (prokaryote, endosymbiont) --> TIR-NOD-LRR (already in immunity from start? Other functions?) --> (TIR-NOD-LRR-WRKY), CC-NOD-LRR --> BED-NOD-LRR
In addition there are C- and N-terminal truncations that have occured at multiple occasions, which are not included in this linear phylogeny.
Fungi, "protist" and algae NOD proteins:
TIR-NOD-TPR --> NOD-TPR
TIR-NOD-WD40 --> NOD-WD40
Conclusion: Both "parental" classes of domain structures were present after the plant-animal split.
The TIR domain appears to have split from the NOD domain prior to the plant/animal split (based on animal-related TIR domains present in green and brown algae). This domain has then associated to rather different proteins in the two lineages. Surprisingly, no TIR domains could be found in any fungal genome I checked.
So my question (a rather open discussion) is whether these additional eukaryotic supergroups (according to figure S1 it is unclear in which order the different supergroups diverged from each other) could enhance the resolution of the evolutionary history of these domains and their association to other domains.