Chromosomal organization and nucleotide sequence of the genes coding for the elongation factors G and Tu of the apple proliferation phytoplasma

Genes coding for elongation factors G (Sus) and Tu (tuf) of the non-cultura ble apple proliferation (AP) phytoplasma were cloned and sequenced. Arrange ment of these genes and identification of the ribosomal protein gene rps7 u pstream of the fus gene suggest a transcriptional organization similar to t hat of the streptomycin operon of Escherichia coli and other bacteria. The fus and tuf genes from other tested phytoplasmas were found to be similarly linked as in the AP agent. Thus, it is likely that they show a similar chr omosomal arrangement. This organization would be in contrast to that of the phylogenetically distinctly different culturable mollicutes of the genus M ycoplasma in which the tuf and fus genes are separately transcribed. (C) 19 99 Elsevier Science B.V. All rights reserved.