Characterization of four ribosomal RNA operons in the genome of Agrobacterium tumefaciens MAFF301001.

Abstract

The four ribosomal RNA (rrn) operons rrnA, rrnB, rrnC and were identified, sequenced completely and characterized individually rrnD in the whole genome of A tumefaciens MAFF301001. These rrn operons were located in the two topologically different chromosomal DNAs; rrnA and rrnD in the linear chromosome and rrnB and rrnC in the circular chromosome. Each operon coded for three ribosomal RNA subunit genes; 16S, 23S and 5S rRNA. The 16S-23S internal transcribed spacers (ITS) of the four rrn operons contain genes for tRNA-Ile and tRNA-Ala and tRNA-Met downstream of 5S rDNA gene while the intergenic spacer between 23S rDNA and 5S rDNA lacked tRNA genes. Sequence alignment of 23S rRNAs of A. tumefaciens MAFF301001 and C58 strains showed unrelated sequences near the 5' end region suggesting the presence of intervening sequence (IVS). Primer extension analyses revealed that the primary transcription products for 16S and 23S rRNAs are 1497 and 2877 bases long, respectively.