GENE ORGANIZATION AND TRANSCRIPTIONAL ANALYSIS OF THE SPIROPLASMA-CITRI RPSB TSF/X OPERON/

The nucleotide sequence of a 6863-bp Spiroplasma citri DNA fragment co mprising the spiralin gene was determined. Sequence analysis revealed eight putative ORFs that encode ribosomal protein S2, elongation facto r Ts, spiralin, 6-phosphofructokinase, pyruvate kinase, and three unid entified proteins (A, B, and X). The gene organization reported here i s different from that previously published. Northern blot analysis of rpsB, tsf, and x transcripts indicates that these genes are organized into a single transcriptional unit (operon). However, the detection of an additional transcript corresponding to the rpsB gene alone suggest s that a transcriptional mechanism should occur in the 3' region of th e rpsB gene, allowing a conditional transcription termination.