ANALYSIS OF THE PRIMARY STRUCTURE OF THE LEADER SEQUENCE OF THE 16S rRNA GENE FROM Vicia faba

The leader sequence of the 16S rDNA gene from the Vicia faba chloroplast is reported in this paper. In this sequence, F1 and the X-protein gene are absent which can be explained by the genome rearrangement. Comparison of F3 of V. faba and those of other plant indicates that: (ⅰ) the conservative regions in F3 of V. faba are more consistent with the consensus sequences, (ⅱ) in F3 of V. faba, the region between --10 and the start point is richer in A-T, and (ⅲ) a stable stem-loop structure can form upstream the 5' end of the 16S rRNA gene in Brassica napus, tobacco, maize and spinach, however, no such structure could form in V. faba. We conclude that the rDNA promoter of V. faba is more efficient and the single rDNA copy fulfils the role of the double rDNA copies by enhancing the rDNA transcription.