SWI/SNF family ATPases play diverse cellular roles, with different classes specialized for different substrates and outcomes.
Furthermore, clades within the AA10 family are specialized for different substrates and subclade A has undergone diversifying selection at surface-exposed regions of the protein.
Some phylogenetic groups such as Alphaproteobacteria, Gammaproteobacteria and Bacteroidetes are highly diverse, and different subgroups can be specialized to utilize different substrates (Teeling et al. 2012) and thus might be stimulated under specific environmental conditions.
In contrast, broad, brush-like jaws of the latter group appear specialized for scraping benthic substrates to dislodge and ingest fractions of detritus and biofilm that are lower in protein content [ 1].
Also Aphotopontius acanthinus and Stygiopontius hispidulus were recently detected in samples taken about 1 km off-axis in the 9°50'N EPR region (SG pers. obs).. Apparently, dirivultids are specialized to colonize hard substrate.
This enzyme may be specialized for the adenine substrate, posterior to the divergence of the LCA, from a broad-specificity ancestor, similar to the HPRTases (2.4.2.8).
Subfunctionalization of duplicated enzymes might occur at the level of gene expression leading, e.g., to tissue-specific expression ([ 56] and references therein) or at the protein level, when a duplicate becomes specialized for a certain substrate [ 64].
For example, D. sechellia and D. erecta, which are specialized to grow on particular substrates, have lost gustatory receptors and detoxification genes (Drosophila 12 Genomes Consortium et al. 2007; Dworkin and Jones 2009).
Ódor and van Hees [51] found that in Hungarian beech forests, thin logs could function as substrate for bryophytes specialized on CWD only when boulder cover was high.
Regarding the function of ancestral HME/HAE1-like proteins, it is not possible, standing to data presented in this work, to infer whether they were already specialized in recognizing a specific substrate or not.
