Chloroflexi (class) - Genomics

Genomics

Comparative genomic analysis has recently refined the taxonomy of the class Chloroflexi, dividing the Chloroflexales into the suborder Chloroflexineae consisting of the family Oscillachloridaceae and the family Chloroflexaceae, and the suborder Roseiflexineae containing family Roseiflexaceae. The revised taxonomy was based on the identification of a number of conserved signature indels (CSIs) which serve as highly reliable molecular markers of shared ancestry. Comparative analyses of Chloroflexi genomes have identified 5 CSIs in different important proteins, such as GroES and Tryptophan synthase, that are uniquely shared by all sequenced species/strains of the Chloroflexi class, but are not found in any other bacteria. Another 9 CSIs have been identified in a number of proteins, including important photosynthesis related proteins such as Magnesium chelatase, that are specific for all or most of the species from the order Chloroflexales. Within the Chloroflexales, 3 CSIs specific for Chloroflexaceae, 4 CSIs specific for Roseiflexaceae, and 7 CSIs specific for the suborder Chloroflexineae, which consists of Chloroflexaceae and Oscillochloridaceae have also been identified in various proteins. Two of the CSIs uniquely found in the Chloroflexaceae family, a 4 aa insert in the protein pyruvate flavodoxin/ferredoxin oxidoreductase (PFOR) and a 2 aa insert in the protein magnesium-protoporphyrin IX monomethyl ester cyclase (ACSF), are located in proteins which play important roles in photosynthesis and are only found in photosynthetic organisms.