Open AccessThe organization of two rRNA ( rrn ) operons of the slow‐growing pathogen Mycobacterium celatum provides key insights into mycobacterial evolution
Author(s) -
StadthagenGomez Gustavo,
HelgueraRepetto A. Cecilia,
CernaCortes Jorge F.,
Goldstein Richard A.,
Cox Robert A.,
GonzalezyMerchand Jorge A.
Publication year - 2008
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2007.01050.x
Subject(s) - ribosomal rna , operon , biology , 23s ribosomal rna , internal transcribed spacer , genetics , genome , gene , 16s ribosomal rna , phylogenetic tree , rna , escherichia coli , ribosome
The slow‐growing Mycobacterium celatum is known to have two different 16S rRNA gene sequences. This study confirms the presence of two rrn operons and describes their organization. One operon ( rrn A) was found to be located downstream from mur A and the other ( rrn B) was found downstream from tyr S. The promoter regions were sequenced, and also the intergenic transcribed spacer (ITS1 and ITS2) regions separating the 16S rRNA, 23S rRNA and 5S rRNA gene coding regions. Analysis of the RNA fraction revealed that rrnA is regulated by two (P1 and PCL1) promoters and rrn B is regulated by one (P1). These data show that the two rrn operons of M. celatum are organized in the same way as the two rrn operons of classical fast‐growing mycobacteria. This information was incorporated into a phylogenetic analysis of the genus based on both 16S rRNA gene sequences and (where possible) the number of rrn operons per genome. The results suggest that the ancestral Mycobacterium possessed two ( rrn A and rrn B) operons per genome and that subsequently, on two separate occasions, an operon ( rrn B) was lost, leading to two clusters of species having a single operon ( rrn A); one cluster includes the classical pathogens and the other includes Mycobacterium abscessus and Mycobacterium chelonae .