Organization of a Sulfolobus solfataricus gene cluster homologous to the Escherichia coli str operon

The Sulfolobus solfataricus S12, S7 and S10 ribosomal proteins and the elongation factor 1 alphagenes are organized in a sequence analogous to that in the Escherichia coli str operon. Northern analysis showed that the S12 gene belongs to a transcript different from that corresponding to the other three genes. Compared to the Sulfolobus acidocaldarius S12 and to the Methanococcus vannielii S7 proteins, the S. solfataricus S12 and S7 proteins were 33 and 47 amino acids longer respectively. These differences were eliminated if the 5' flanking regions of the S. acidocaldarius S12 and the M. vannielii S7 genes were translated from a different start codon. Despite the structural similarities between the archaeal and the bacterial str operons the S. solfataricus ribosomal proteins S12, S7 and S10 are more similar to the eukaryotic counterparts.