Synergistetes - Comparative Genomics and Molecular Signatures

Comparative Genomics and Molecular Signatures

Recent comparative analyses of sequenced Synergistetes genomes have led to identification of large numbers of conserved signature indels (CSIs) in protein sequences that are specific for either all sequenced Synergistetes species or some of their sub-clades that are observed in phylogenetic trees. Of the CSIs that were identified, 32 in widely distributed proteins such as RpoB, RpoC, UvrD, GyrA, PolA, PolC, MraW, NadD, PyrE, RpsA, RpsH, FtsA, RadA, etc., including a large >300 aa insert in the RpoC protein, are present in various Synergistetes species, but except for isolated bacteria, these CSIs are not found in the protein homologues from all other organisms. These CSIs provide novel molecular markers for distinguishing Synergistetes species from all other bacteria. Seven other CSIs in important proteins including a 13 aa in RpoB were found to be uniquely present in Jonquetella, Pyramidobacter and Dethiosulfovibrio species indicating a close and specific relationship among these bacteria, which is also strongly supported by phylogenetic trees. Fifteen addition CSIs that were only present in Jonquetella and Pyramidobacter indicate a close association between these two species. Lastly, a close relationship between the Aminomonas and Thermanaerovibrio species is also supported by 9 identified CSIs. The identified molecular markers provide reliable means for the division of species from the phylum Synergistetes into intermediate taxonomic ranks such as families and orders.