|Slide culture of a Streptomyces species|
Rainey et al. 1997
Waksman & Henrici 1943
Streptomycetaceae is a family of Actinobacteria, making up to the monotypic suborder Streptomycineae. It includes the important genus Streptomyces. This was the original source of many antibiotics, namely streptomycin. Streptomycin was the first antibiotic against tuberculosis.
Sequence alignments of actinobacterial genomes have led to the identification of 3 conserved signature indels which are unique to the order Streptomycetales. The enzyme PBGD contains a 4 amino acid insertion which is present in all Streptomyces species and Kitasatospora setae, but not any other Actinobacteria. Similarly, a 1 amino acid insertion is present in a conserved region of adenylate kinase and is found in all Streptomyces species and K. setae, but is not found in any other Actinobacteria. 5 conserved signature proteins have also been identified which are present in various sequenced Streptomyces species but not in K. setae; however, as the complete genome of K. setae has not yet been sequenced, it is possible that these proteins may be present in K. setae. Additionally, 11 conserved signature proteins have been identified which are found in all sequenced Streptomyces species and K. setae. It is believed that these proteins are unique to the Streptomycetales order and thus provide molecular markers which can be used to distinguish this group from the rest of the Actinobacteria. Phylogenetic trees indicate that the order Catenulisporales is closely related to the order Streptomycetales. This inference is supported by a 1 amino acid conserved signature indel which is uniquely found in all Streptomycetales species and Catenulisporales acidiphilia, the only Catenulisporales species whose complete genome has been sequenced. Additionally, 3 conserved signature proteins have been identified which are found in all Streptomycetales species and C. acidiphilia. Both the conserved signature indel and the conserved signature proteins provide evidence that the orders Streptomycetales and Catenulisporales are closely related.