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Novel expression of the ribosomal RNA genes in the extreme thermophile and archaebacterium Desulfurococcus mobilis
Author(s) -
Kjems Jørgen,
Garrett Roger A.
Publication year - 1987
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1987.tb02678.x
Subject(s) - operon , ribosomal rna , biology , thermophile , genetics , gene , bacteria , escherichia coli
The single 16S/23S rRNA operon of the sulfur‐dependent extreme thermophile Desulfurococcus mobilis is transcriptionally uncoupled from the single 5S RNA gene. Transcription of the former operon initiates at five sites, P5–P1. RNA polymerases intiating at sites P5–P2 terminate and then reinitiate at the next downstream site, thus providing a queue of polymerases at the primary initiation site P1. Putative promoter sequences that are AT‐rich lie upstream from each site. Termination occurs at two main sites within long pyrimidine sequences downstream from the 23S RNA gene. A processing site for both large RNAs occurs at a secondary structural feature common to other archaebacterial rRNAs. Transcription of 5S RNA starts mainly at P1/5S at the 5′ end of the gene with a low level of initiation from two upstream sites; a similar mechanism of initiation–termination–reinitiation appears to operate and the sites are all preceded by AT‐rich promoter‐like sequences. Termination occurs a few nucleotides beyound the 3′ end of the 5S RNA. The mature RNA contains ˜133 nucleotides, has a 78% GC bp content and exhibits an unusually extended version of helix I with heterogeneous ends. The expression of the rRNA genes shows characteristics of eukaryotes, eubacteria and archaebacteria.