Identification of chromosomal alpha-proteobacterial small RNAs by comparative genome analysis and detection in Sinorhizobium meliloti strain 1021.

Background: Small untranslated RNAs (sRNAs) seem to be far more abundant than previously believed. The number of sRNAs confirmed in E. coli through various approaches is above 70, with several hundred more sRNA candidate genes under biological validation.

Characterization and expression patterns of Sinorhizobium meliloti tmRNA (ssrA).

tmRNA (ssrA) in Sinorhizobium meliloti is a small RNA annotated by homology with the Bradyrhizobium japonicum sra molecule. Here, this molecule is described in Sinorhizobium meliloti as a model for such molecules in Alphaproteobacteria subgroup-2. Northern blot analysis and mapping of both 5' and 3' ends of this tmRNA allow the identification of two pieces: a 214 nt mRNA-like domain and an 82 nt tRNA-like domain, both highly stable, whereas the premature form is unstable.