Although the chemical identity of polyP has remained unchanged, its function might have become more specialized during the organism diversification from the ancestral cells to apparently simple bacterial cells and the platelets of mammals.
However, it is unlikely that in this case a more specialized database of closely related organisms is available for a better prediction.
Other groups encode fewer CAZymes and are clearly more specialized, but some of these organisms appear to play critical roles in the community by initiating the degradation of complex substrates such as plant cell walls, starch particles and mucin.
Yet we suggest that culture techniques have a much more dramatic bias and greatly overestimate the importance of organisms that are easily cultured and can underestimate the importance of fastidious organisms, which require more specialized culture methods [26].
Specialized interactions help structure communities, but persistence of specialized organisms is puzzling because a generalist can occupy more environments and partake in more beneficial interactions.
This organism appears to be more specialized than the other two in that it is restricted to the use of peptides and amino acids as energy sources, although formate can also be utilized.
Additionally, horticultural species span a wide range of life-history and life-form characteristics, whereas biocontrol organisms necessarily tend to be more specialized (van Klinken and Edwards 2002).
The capacity of Ssa5p Ssa8p to support growth of Y. lipolytica is unknown but our results suggest that they also differ with regard to essential cellular functions in their native context, and that Ssa6p has evolved more specialized function, perhaps related to differences in this organism's environment or metabolic activities.
Overall, our data suggest that both "generalist" GTs that are able to protect the organism against various stresses and more specialized GTs, required only for protection against well defined stresses, coexist inside the cell.
Alternatively, it may be that PATs perform more basic cellular housekeeping functions in relatively simple organisms, which might be more readily compensated for, but take on more specialized roles in more complex animals.
